Parse MySQL ALGORITHM and LOCK options to ALTER TABLE

[mvzink]

Example:

ALTER TABLE tbl_name MODIFY COLUMN col_name column_definition FIRST, ALGORITHM=INPLACE, LOCK=NONE;

See ALTER TABLE docs for syntax and Online DDL Operations docs for semantics.

  | ALGORITHM [=] {DEFAULT | INSTANT | INPLACE | COPY}
  | LOCK [=] {DEFAULT | NONE | SHARED | EXCLUSIVE}

[mvzink]

Forgot to mark this closed by #1745

[mvzink]

Oops, sorry, that didn't fix LOCK!