[pkg/ottl]: add bitwise AND (&) and OR (|) operators

[57Ajay]

Description

This PR adds bitwise AND (&) and OR (|) as native operators in OTTL math expressions, addressing the first part of #45560.

These operators enable bitwise flag manipulation directly in OTTL statements without requiring custom converter functions:

transform:
  log_statements:
    - context: log
      statements:
        - set(attributes["masked"], attributes["flags"] & 0xFF)
        - set(attributes["combined"], attributes["a"] | attributes["b"])

Implementation

Bitwise operators are implemented as grammar-level operators, following the same architecture as the existing arithmetic operators (+, -, *, /).

Grammar changes (grammar.go):

• Added OpBitwiseAnd and OpBitwiseOr lexer tokens
• Added bitwiseAndTerm, opBitwiseAndTerm, bitwiseOrTerm, opBitwiseOrTerm AST nodes
• Rewired mathExpression to route through the new precedence levels
• Updated value lookahead to include new tokens

Evaluation changes (math.go):

• Added evaluateBitwiseOrTerm and evaluateBitwiseAndTerm evaluation functions
• Added performBitwiseOp for int64-only bitwise execution
• Bitwise ops on non-int64 operands return a clear error

Operator precedence (highest → lowest):

Precedence	Operators	Description
1	* /	Multiplication, Division
2	+ -	Addition, Subtraction
3	&	Bitwise AND
4	|	Bitwise OR

This matches the precedence in Go, C, Java, and Python.

Type constraints

• Operands must be int64. Using float64, time.Time, or time.Duration returns an error: "bitwise operations require int64 operands".

Testing

• Unit tests (math_test.go): 11 new passing tests covering AND, OR, precedence, paths, parentheses, mixed arithmetic+bitwise
• Error tests (math_test.go): 2 new tests verifying float operand rejection
• Lexer tests (lexer_test.go): 3 new tests for &, | tokens and combined expressions
• Parser tests (parser_test.go): existing ASTs updated for new grammar structure
• E2E tests (e2e/e2e_test.go): 5 new integration tests through the full parser --> evaluator pipeline
• Manual verification: built otelcontribcol, tested with transform processor + OTLP HTTP receiver + debug exporter, all 6 expressions produced correct results

Scope

This PR implements & and | only. Remaining bitwise operators (^, ~, <<, >>) can follow in subsequent PRs once this approach is validated by code owners.

[florianl]

Works fine here and enables interesting options

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[57Ajay]

Hey, @edmocosta @TylerHelmuth @evan-bradley @bogdandrutu, a gentle reminder if you have some time can you please review this PR. I would love to hear your feedback on this..