Enhance optimizer to support constant maps

[phsym]

This pull request enhances the optimizer to support constant propagation for map access expressions, enabling compile-time evaluation of property and index lookups when the map is a constant known at compile/optimization time. It also adds comprehensive tests to ensure these optimizations work as intended.

Optimizer enhancements for constant map access:

• Added support for optimizing property access (var.property) when var is a constant map, allowing direct replacement with the corresponding value at compile time.
• Added support for optimizing index access (var[property]) when var is a constant map and property is a string or a constant string variable, enabling constant folding for these expressions.
• Property access on constant map literals #{a: 42}[property] when property is a constant string variable is also optimized at compile time, removing the need for runtime lookup.

Testing improvements:

• Added a new test, test_optimizer_const_map, which verifies that constant map optimizations work for both property and index access patterns, including dynamic key access.

[schungx]

Just a minor nitpick in the comments.

And is_some_and is not supported in MSRV so better avoid it.

Great work. This will be very useful in cases where constant maps are used as a form of enum or avoiding the creation of a large number of constant variables.

My own scripts have tons of those so this will be very helpful.

[phsym]

@schungx thank you for your quick feedback. I made the updates based on your comments