MDEV-13594: Implement -> and ->> JSON path operators

[kjarir]

[MDEV-13594] Implement JSON -> and ->> Operators

Summary

This PR implements MySQL-compatible JSON shorthand operators in the MariaDB server. These operators provide a more concise syntax for extracting and unquoting JSON data:

• column->'$.path' is equivalent to JSON_EXTRACT(column, '$.path')
• column->>'$.path' is equivalent to JSON_UNQUOTE(JSON_EXTRACT(column, '$.path'))

Details

• Lexer: Lookahead added to the - character state to identify -> and ->> sequences in sql/sql_lex.cc.
• Parser: Grammar rules added to sql/sql_yacc.yy under primary_expr. To resolve shift/reduce ambiguities, the Left-Hand Side (LHS) has been restricted to primary_base_expr (non-recursive).
• Precedence: Correctly configured as left-associative with higher precedence than arithmetic operations.
• Conflicts: Bison conflicts updated from 70/71 to 72/73 to allow for the new JSON operator rules.

Performance & Quality

• ASAN/UBSAN: Verified with an ASAN-enabled build on macOS.
• MTR: Successfully added and passed a new test suite: json.mdev13594.

./mariadb-test-run.pl json.mdev13594

Status: [ pass ]

[kjarir]

@gkodinov @grooverdan There was a huge mistake from my side, so i moved the PR to this.