Add support for libsql

[briancbarrow]

This should resolve issues connecting to a libsql database. Closes the issue I opened #192

All I did was copy the sqlite3store folder contents over into the new folder and updated the variables to ? instead of $1 etc.

Please let me know if any changes are needed.

[aranw]

Hey I was wondering whether there's any updates on getting this addition merged?

[briancbarrow]

@alexedwards I just wondered if you had a chance to look at this one yet? No pressure. I understand how busy life can get.

[alexedwards]

@briancbarrow Sorry for the slow reply on this. I'm just trying to work through the backlog now.

I'm at a point where I don't want to merge more store implementations into the main repository --- there are enough to maintain already and most of them I don't ever use (which makes running tests and maintaining them when problems arise awkward).

Would you be happy instead to host this store implementation in your own GitHub repository? And then we can list it and link to it from the main README?

[briancbarrow]

@alexedwards That makes sense. I haven't been using it lately so I don't want to maintain it either. @aranw You are welcome to take what I've done though and make it your own if you'd like.