feat: added sqlite3store context cancelation

[TobiasGleiter]

I've added four funcs to add context cancelation to the sqlite3store:

1. AllCtx
2. FindCtx
3. CommitCtx
4. DeleteCtx

• These have the exact same implementation as the funcs without context. The only difference is that we call sql funcs with context cancelation.
• Instead of having two implementations, I reused the context funcs to have one source of truth.
• For the comments, I only appended the suffix Ctx to the funcs. Same description as before.

One other note: I've suggested in #256 to add deleteCtx func which cannot be easily implemented and might not be an issue at all. No changes are sometimes better.

Closes #256