feat: ImportExpr and ImportFromExpr

[apkrelling]

Pull Request description

This PR adds ImportExpr and ImportFromExpr.
This PR is an attempt to solve #88 .

• added new ASTKind's
• created ImportExpr and ImportFromExpr classes
• updated __init__.py to include the new imports and classes in the __all__ list
• added the new classes ad visit methods in transpilers/python.py
• added tests in tests/transpilers/test_python.py
• added tests in tests/test_packages.py

How to test these changes

from astx import ImportExpr, ImportFromExpr, AliasExpr
from astx.transpilers import python as astx2py

# ImportExpr
# Create alias expressions
alias1 = AliasExpr(name="pi")
alias2 = AliasExpr(name="sqrt", asname="square_root")

# Create an import expression
import_expr = ImportExpr([alias1])
import_expr.get_struct()

# Initialize the generator
generator = astx2py.ASTxPythonTranspiler()

# Generate Python code
generated_code = generator.visit(import_expr)

# print generated code
generated_code

# Create an import-from expression
import_from_expr = ImportFromExpr(module="math", names=[alias1, alias2])

import_from_expr.get_struct(simplified=True)

# Initialize the generator
generator = astx2py.ASTxPythonTranspiler()

# Generate Python code
generated_code = generator.visit(import_from_expr)

# print generated code
generated_code

Pull Request checklists

This PR is a:

• bug-fix
• new feature
• maintenance

About this PR:

• it includes tests.
• the tests are executed on CI.
• the tests generate log file(s) (path).
• pre-commit hooks were executed locally.
• this PR requires a project documentation update.

Author's checklist:

• I have reviewed the changes and it contains no misspelling.
• The code is well commented, especially in the parts that contain more
  complexity.
• New and old tests passed locally.

Additional information

Reviewer's checklist

Copy and paste this template for your review's note:

## Reviewer's Checklist

- [ ] I managed to reproduce the problem locally from the `main` branch
- [ ] I managed to test the new changes locally
- [ ] I confirm that the issues mentioned were fixed/resolved .

[apkrelling]

The ascii AST viz has been fixed. now we have something like the outputs below:

Examples of how to test this:

from astx.packages import (
    AliasExpr,
    ImportFromStmt,
    ImportStmt,
    ImportExpr, 
    ImportFromExpr
)

# AliasExpr
alias1 = AliasExpr(name="pyplot", asname="plt")
alias1
alias1.get_struct()

# ImportStmt
alias1 = AliasExpr(name="math")
alias2 = AliasExpr(name="matplotlib", asname="mtlb")
# Create an import statement
import_stmt = ImportStmt(names=[alias1, alias2])
import_stmt
import_stmt.get_struct()

# ImportFromStmt
alias4 = AliasExpr(name="pyplot",asname="plt")
import_from_stmt = ImportFromStmt(module="matplotlib",names=[alias4], level=0)
import_from_stmt
import_from_stmt.get_struct()

# ImportFromStmt
alias2 = AliasExpr(name="matplotlib", asname="mtlb")
import_from_stmt = ImportFromStmt(names=[alias2], level=1)
import_from_stmt
import_from_stmt.get_struct()

# ImportExpr
alias1 = AliasExpr(name="sqrt", asname="square_root")
alias2 = AliasExpr(name="pi")
import_expr = ImportExpr([alias1, alias2])
import_expr
import_expr.get_struct()

# ImportFromExpr
alias1 = AliasExpr(name="pyplot", asname="plt")
import_from_expr = ImportFromExpr(module="matplotlib",names=[alias1])
import_from_expr
import_from_expr.get_struct()

I believe now it's good to go.

[apkrelling]

@xmnlab the problem with graphviz AST viz has been solved.

[github-actions]

🎉 This PR is included in version 0.16.0 🎉

The release is available on:

• 0.16.0
• GitHub release

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