chore(iast): optimize iast by migrating should_iast_patch function to c (#12774)

**TL;DR: Before this PR, IAST startup time was x5,16 lower than an
application without IAST startup time
After this PR, IAST startup time was x2,79**

## Description
In this PR, we aim to improve the startup times of an application when
IAST (Interactive Application Security Testing) is enabled. The
following improvements have been made:

 ### Performance improvements
- These changes aim to streamline the codebase, improve the
functionality of the IAST module, and remove outdated or redundant
code.When reading the source code of a module for transformation with
AST, it is now done in binary mode, which is **30% faste** as shown in
this gist:
https://gist.github.com/avara1986/8e31a23978b5eecd9dc8f2f3135060b0. The
execution times are:
  - `open("r")`: 0.9285 secs
  - `open("rb")`: 0.6362 secs
- The function `should_iast_patch` has been migrated to C. By comparing
the original function with the new one using the following `timeit`
command, is **40% faster**.
  ```
  # refactor
python -m timeit -n 5000000 -r 5 -u usec -s "from
ddtrace.appsec._iast._ast import
  iastpatch""iastpatch.should_iast_patch('mimodulo.submodulo')" 
  # main
python -m timeit -n 5000000 -r 5 -u usec -s "from
ddtrace.appsec._iast._ast.ast_patching import _should_iast_patch"
  "_should_iast_patch('package.mypackage')"
  ```

- I wanted to migrate `exec` to `PyEval_EvalCode` but the results are
very revealing, exec is approximately **17% faster**. The results of
this gist
https://gist.github.com/avara1986/ae2a65dca1b90afa762af67db680bc2b
  - `exec`: mean time of 0.083023 seconds
  - `PyEval_EvalCode`: mean time of 0.099550 seconds

By combining all these changes, the microbenchmarks for startup times
show that the baseline takes 2.46 seconds, while this branch takes 1.24
seconds, making it **1.99x faster**.

 ### Performance analysis
The `_should_iast_patch` logs are under asm_config._iast_debug because
Debug mode has a significant performance impact, making the function
between 1.14x and 3.08x slower
```
Benchmark Results
--------------------------------------------------------------------------------
Module Name                    Debug Time (s)       No Debug Time (s)    Ratio     
--------------------------------------------------------------------------------
os                                    0.017021            0.005522       3.08x
requests                              0.023237            0.020418       1.14x
ddtrace.appsec._iast                  0.024511            0.012280       2.00x
non.existent.module                   0.023403            0.011170       2.10x
```
Branch deployed in rel-env and no leaks found:

![image](https://github.com/user-attachments/assets/faaa6ead-6c48-4f05-944b-5d29ed338d9a)


## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Author: avara1986

ddtrace/appsec/_iast/__init__.py

@@ -92,11 +92,6 @@ def enable_iast_propagation():
     global _iast_propagation_enabled
     if _iast_propagation_enabled:
         return
-    # We need to preload the package_distributions because if we call importlib_metadata inside a module hook
-    # it raises a circular-import
-    from ddtrace.internal.packages import get_package_distributions
-
-    get_package_distributions()
 
     log.debug("iast::instrumentation::starting IAST")
     ModuleWatchdog.register_pre_exec_module_hook(_should_iast_patch, _exec_iast_patched_module)

ddtrace/appsec/_iast/_ast/CMakeLists.txt

@@ -0,0 +1,12 @@
+cmake_minimum_required(VERSION 3.10)
+project(iastpatch C)
+
+find_package(Python3 REQUIRED COMPONENTS Development)
+
+add_library(iastpatch MODULE iastpatch.c)
+
+target_include_directories(iastpatch PRIVATE ${Python3_INCLUDE_DIRS})
+
+target_link_libraries(iastpatch PRIVATE ${Python3_LIBRARIES})
+
+set_target_properties(iastpatch PROPERTIES LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}")