Make pcommon value comparable

[alexcams]

Description

Adds support for comparing pcommon.Value in the OTTL ValueComparator. Previously, pcommon.Value was not handled, comparisons involving attribute values (which are pcommon.Value at runtime) would fall through to Go's == operator, failing for inequality operators (<, <=, >=, >).

• comparePValues(a, b pcommon.Value) handles Value-vs-Value with a same-type fast path (typed accessors, zero allocations)
• comparePValue(a pcommon.Value, b any) handles Value-vs-raw-type by extracting the typed value and delegating to existing compareXXX functions
• Swap pre-check in compare() — when b is a pcommon.Value but a is not, swaps operands with reverseOp so all unwrapping lives in one place

OTTL expressions like attributes["status_code"] > 200 or attributes["a"] >= attributes["b"] now work correctly with all comparison operators on all value types (int, float, string, bool, bytes, map, slice, empty).

Link to tracking issue

Resolves #49170

Testing

Added propper test cases covering many different scenarios.

Documentation

Documentation added to this PR at LANGUAGE.md file.

[alexcams]

/rerun

[edmocosta]

Thanks for working on this @alexcams!

[alexcams]

@edmocosta I've addressed all comments abobe. Thanks for the review :)

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Merged · refreshed 2026-08-05 19:13 UTC

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[edmocosta]

LGTM! @TylerHelmuth @evan-bradley could you please take a look and share your thoughts? Thanks!