feat: add support for excluding table data during export

[astappiev]

Introduces the --exclude_tables_data option to the wp db export command, allowing users to export only the structure of specified tables while excluding their data.

Warning: only supported by MariaDB 10.1 and later. As far as I know, not supported by MySQL.

Resolves #289

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/DB_Command.php	25.00%	6 Missing ⚠️

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[gemini-code-assist]

Code Review

The pull request successfully introduces the --exclude_tables_data option to the wp db export command, which is a valuable addition for users needing to export table structures without their data. The implementation follows the existing patterns in the codebase. I have suggested a few improvements to make the logic more robust, specifically regarding input sanitization (handling spaces in the comma-separated list) and providing a clearer error message when the option is used on unsupported database systems (MySQL), as noted in the PR description.

[gemini-code-assist]

The current implementation has a few robustness issues:

1. Database Compatibility: As noted in the PR description, this flag is MariaDB-specific. Adding an explicit check for the database type allows us to provide a helpful WP-CLI error message instead of a cryptic shell error from mysqldump.
2. Input Sanitization: The trim() on line 745 is applied to the concatenated DB_NAME . '.' . $table string. If the user provides a list like table1, table2 (with a space), the resulting argument becomes dbname. table2, which will cause mysqldump to fail. The trim() should be applied to the $table variable individually.
3. Type Safety: If the flag is passed without a value (e.g., --exclude_tables_data), get_flag_value returns true. The subsequent trim() and explode() calls on a boolean can lead to unexpected behavior (e.g., trying to ignore a table named dbname.1).

		$exclude_tables_data = Utils\get_flag_value( $assoc_args, 'exclude_tables_data' );
		if ( isset( $exclude_tables_data ) ) {
			unset( $assoc_args['exclude_tables_data'] );
			if ( is_string( $exclude_tables_data ) && '' !== trim( $exclude_tables_data ) ) {
				if ( 'mariadb' !== Utils\get_db_type() ) {
					WP_CLI::error( 'The --exclude_tables_data option is only supported by MariaDB.' );
				}

				$tables = explode( ',', trim( $exclude_tables_data, ',' ) );
				foreach ( $tables as $table ) {
					$table = trim( $table );
					if ( '' === $table ) {
						continue;
					}
					$command           .= ' --ignore-table-data';
					$command           .= ' %s';
					$command_esc_args[] = DB_NAME . '.' . $table;
				}
			}
		}