feat(mysql): add support for vector indices #691

Job	Run time
Compile SQLite (live/sqlite)	1m 18s
Compile MySQL (live/mysql)	1m 12s
Clippy	1m 11s
Compile SQLite (discovery/sqlite)	1m 7s
Compile Postgres (live/postgres)	1m 11s
Compile MySQL (discovery/mysql)	1m 4s
Compile SQLite (writer/sqlite)	1m 1s
Compile Postgres (discovery/postgres)	1m 6s
Compile MySQL (writer/mysql)	1m 8s
Rustfmt	13s
Compile Postgres (writer/postgres)	1m 7s
Unit Test	1m 20s
Postgres (14.4, live/postgres)	1m 10s
Postgres (14.4, discovery/postgres)	1m 13s
Postgres (14.4, writer/postgres)	1m 4s
MariaDB (10.6, live/mysql)	48s
MySQL (8, live/mysql)	50s
MariaDB (10.6, discovery/mysql)	45s
MySQL (8, discovery/mysql)	47s
MariaDB (10.6, writer/mysql)	50s
MySQL (8, writer/mysql)	53s
MySQL (5.7, live/mysql)	58s
MySQL (5.7, discovery/mysql)	57s
MySQL (5.7, writer/mysql)	49s
SQLite (live/sqlite)	25s
SQLite (discovery/sqlite)	18s
SQLite (writer/sqlite)	19s
	25m 4s

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