PreparedSQLPlaceholders.UnquotedComplexPlaceholder: allow for tablenames in backticks

Is your feature request related to a problem?

Given the following code snippet:

$wpdb->query(
	$wpdb->prepare(
		'TRUNCATE TABLE `%1$s`',
		plugin_get_table_name( 'Name' )
	)
);

WPCS will currently throw the following warning:

WARNING | Complex placeholders used for values in the query string in $wpdb->prepare() will
          NOT be quoted automagically. Found: %1$s.
          (WordPress.DB.PreparedSQLPlaceholders.UnquotedComplexPlaceholder)

Describe the solution you'd like

In this particular case, I believe the warning should not be thrown.
Instead the sniff should recognize the backticks as valid "quotes" for a table name.

Note: this should only be accepted for table names, so, the sniff should probably look for TABLE or FROM before the placeholder.

Some research may need to be done into the various SQL syntaxes to make sure that the sniff recognizes the correct keywords and doesn't miss any real unquoted placeholders.

Start by locating the PreparedSQLPlaceholders.UnquotedComplexPlaceholder sniff and its tests, then inspect how placeholders inside backticks are classified. Research the supported SQL syntax around TABLE and FROM before deciding which table-name cases are valid; done means valid backtick-quoted table placeholders no longer warn while unquoted value placeholders still do.