feature addition: add mariadb vector store

[rusher]

Here is the MariaDB database store implementation.

not just another one : https://mariadb.org/projects/mariadb-vector/ :)

[tzolov]

Thank you @rusher
Well done. I've covered all corners including the portable filter expression. Thanks.

One of the auto-conf tests is failing for me. Can you have a look?

[rusher]

Right, i have corrected the test. Must i merge the commit into one ?

[tzolov]

Thanks @rusher , I'll give it a try. Please don't squash the commits. I will do it before the merge

[tzolov]

Thank you @rusher !
Cleared, rebased, squashed and merged at 0b00e6f