Improve the CMake project wizard template

[mbooth101]

The hello world CMake project template is extremely basic and generates deprecation warnings out-of-the-box:

Configuring in: /home/mbooth/runtime-cdt-0/MrProj/build/default
cmake -G Unix Makefiles -DCMAKE_EXPORT_COMPILE_COMMANDS=ON /home/mbooth/runtime-cdt-0/MrProj
CMake Deprecation Warning at CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 2.8.12 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions.

And will not build at all if you name the project something containing a space:

CMake Error: Could not find cmake module file: CMakeDetermineProjCompiler.cmake
CMake Error: Error required internal CMake variable not set, cmake may not be built correctly.
-- Configuring incomplete, errors occurred!
See also "/home/mbooth/runtime-cdt-0/A Proj/build/default/CMakeFiles/CMakeOutput.log".
Missing variable is:
CMAKE_Proj_COMPILER_ENV_VAR
CMake Error: Error required internal CMake variable not set, cmake may not be built correctly.

Every currently supported distro of Linux that I checked comes with CMake > 3 so I propose we make the template a bit better. This change fixes the deprecation warnings by bumping the min version of CMake to 3.10 (still a very old version) and takes advantage of some features from CMake > 3, like showing how to set some project configuration details, and showing how to implement the common idiom of generating configuration headers.

Project names containing spaces is also allowed by this patch by using freemarker syntax to remove them where necessary in the template.

[mbooth101]

Hi @15knots, what do you think about this improvement?

[github-actions]

Test Results

     612 files       612 suites   19m 0s ⏱️
10 253 tests 10 230 ✔️ 21 💤 2 ❌
10 216 runs  10 193 ✔️ 21 💤 2 ❌

For more details on these failures, see this check.

Results for commit 8b29717.

[15knots]

+1
(Although I'm not using CDT's core cmake build at all)

[jonahgraham]

LGTM too.