Add python Evaluator module

[pljakobs]

Introduce an 'Evaluator' Class to Tools/Python/evaluator.py designed to evaluate logical and mathematical expressions in various build-time configurations like ConfigDB

Key features:

• implements a set of arithmetic functions (+,-,*,/, pow2, log2)
• implements logical operations (&&, ||, ! and !=)
• implements min/max and align_up functions to calculate hardware- specific values such as "how much flash do I need to store x bytes if flash block size is 4096

[what-the-diff]

PR Summary

• New Python script: 'evaluator.py'
  We have added a new script which introduces a specialized language to efficiently handle and compute expressions.

• Introduction of 'Evaluator' class
  This newly implemented class will assist in performing mathematical, binary, logical operations and comparisons. It also comes with some uniquely modeled functions like 'pow2', 'log2', and 'align_up'.

• Environment Variables Processing
  We are also processing environment variables, converting them into boolean (true or false) values with the help of an auxiliary '_is_truthy' function.

• Enhanced Expression Parsing
  We have improved handling and interpretation of expressions using Python's AST library, which should simplify their usage and increase reliability.

• New Documentation: 'evaluator.md'
  A markup file has been created documenting the syntax of our newly introduced specialized language, it's built-in functions and any security precautions taken to prevent any possible compromises, such as injection attacks.

• Automated Test Script: 'evaluator_test.py'
  Finally, we've added a test script to run a variety of tests that will verify the function of our 'Evaluator' class in comparison to the expected results, ensuring their performance matches our standards.

[mikee47]

@pljakobs Are you happy with the changes I've made? The two main changes are:

• Allow custom variable resolution using get_variable callback
• Propagate exceptions rather than returning a string. That might be OK in a CLI but not for use in other code. We cannot know that legitimate return values don't start with 'Error: ' for example.

We may need other features in the future but I think this covers the basics.

[pljakobs]

looks good to me. Thanks for your work!