Defer number literal evaluation to parser

[nsvke]

This PR defers number literal evaluation (underscore stripping, base conversion) and suffix validation from the Lexer to the Parser phase.

Previously, the Lexer eagerly stripped underscores and validated suffixes. This violated source fidelity for procedural macros, causing them to receive mutated strings or fail prematurely on invalid suffixes.

gcc/rust/ChangeLog:

* ast/rust-ast-collector.cc (TokenCollector::visit): Update Token::make_int and Token::make_float calls to include suffix_start and LITERALBASE_DECIMAL.
* expand/rust-macro-builtins-location.cc (MacroBuiltin::column_handler): Pass string length and base to Token::make_int. (MacroBuiltin::line_handler): Likewise.
* lex/rust-lex.cc (Lexer::parse_in_type_suffix): Rename to parse_in_suffix and return string instead of PrimitiveCoreType. (Lexer::parse_in_suffix): Remove underscore stripping to preserve source fidelity for macros. (Lexer::parse_in_exponent_part): Preserve '+' and '-' characters in the raw string. (Lexer::parse_in_decimal): Remove underscore stripping. (Lexer::parse_non_decimal_int_literal): Track suffix start index and pass literal base. (Lexer::parse_non_decimal_int_literals): Use IntegerLiteralBase enum values instead of raw integers. (Lexer::parse_decimal_int_or_float): Track suffix string length and pass base parameters to token creation.
* lex/rust-lex.h: Update method signatures for suffix parsing.
* lex/rust-token.h (enum IntegerLiteralBase): New enum to represent numeric bases.
* parse/rust-parse-impl-expr.hxx: use LiteralResolve functions to evaluate raw token strings.
* parse/rust-parse-impl-pattern.hxx: Use evaluated literal strings for INT and FLOAT tokens.
* parse/rust-parse.cc (resolve_literal_suffix): Move suffix validation logic from lexer to parser. (evaluate_integer_literal): New function to strip underscores and convert to decimal via GMP. (evaluate_float_literal): New function to strip underscores from floats.
* parse/rust-parse.h (evaluate_integer_literal): Declare in LiteralResolve namespace. (evaluate_float_literal): Likewise. (resolve_literal_suffix): Likewise.
* util/rust-token-converter.cc (from_literal): Safely reconstruct raw text and suffix to dynamically determine base and suffix_start for ProcMacros.

gcc/testsuite/ChangeLog:

* rust/compile/deferred-suffix-validation.rs: New test.
* rust/compile/evaluate-integer-or-float.rs: New test.
* rust/compile/tuple-index.rs: New test.

[CohenArthur]

I think this is a really good fix and the implementation looks good! well done @nsvke!