This PR introduces the following changes:

• The CHAR BYTE alias is now supported.

  Previously, BYTE had not been understood to be part of a type alias and was registered only as a reserved keyword.

• Many additional keywords and reserved keywords have been found by changing the mysql GitHub branch from 8.0 to trunk.

  A number of existing keywords have been removed in the mysql keyword list since mysql 8.0, but for backwards compatibility these removals were discarded in the pygments keywords list.

  The result is a number of additions to the list of mysql keywords that pygments recognizes, with zero removals. Note that byte appears to be a removal, but is actually moved up to the tuple of MYSQL_DATATYPES, as noted in the first bullet point above.