fix: parse division in free parameter expressions

[GodHad]

Issue #1251

Description of changes:

• Adds support for parsing / in FreeParameterExpression string constructors by mapping ast.Div to the existing true-division implementation.
• Updates the parameter expression unit tests so FreeParameterExpression("theta/alpha") matches the equivalent expression built with FreeParameter("theta") / FreeParameter("alpha").
• Keeps unsupported division-like operations, such as //, covered by the unsupported binary operation test.

Testing done:

• python -m pytest -o addopts='' test\unit_tests\braket\parametric\test_free_parameter_expression.py
• Result: 27 passed, 4 xfailed

Merge Checklist

General

• I have read the CONTRIBUTING doc
• I used the PR title format described in CONTRIBUTING
• I have updated any necessary documentation, including READMEs and API docs (if appropriate)

Tests

• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have checked that my tests are not configured for a specific region or account (if appropriate)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.