Build: Replace github.com/mattn/go-sqlite3 with a non-CGO alternative

[hairyhenderson]

Why is this needed:

Currently we need to build the Grafana backend with CGO_ENABLED=1 because of our use of github.com/mattn/go-sqlite3. A pure Go alternative is available - github.com/glebarez/go-sqlite.

We should consider using this to simplify our build process (remove cross-compilation considerations, etc).

[grafanabot]

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[hairyhenderson]

Upon reading closer about github.com/glebarez/go-sqlite I realize my initial impression of modernc.org/sqlite was mistaken - I thought the latter had no database/sql driver, hence the former. However both have drivers. The reason glebarez/go-sqlite exists is explained here: https://github.com/glebarez/go-sqlite/issues/96 - essentially:

glebarez/go-sqlite is just a fork of modernc.org/sqlite with slight changes in the driver part (2), to behave more closely to mattn’s CGo driver (https://github.com/mattn/go-sqlite3). this slight changes allowed it to be fully compatible with GORM [...]

This may or may not be relevant, as we're currently using the mattn driver, and that with xorm, which, while different from GORM, raises questions about whether or not modernc.org/sqlite will work without too much trouble on its own.

https://github.com/cvilsmeier/go-sqlite-bench also lists a number of other candidate modules:

(copy/pasted from the README, and annotated by me):

• crawshaw.io/sqlite, a CGO-based solution. This is not a database/sql driver.
  • disqualified (CGO + no driver)
• github.com/eatonphil/gosqlite, a CGO-based solution. This is not a database/sql driver.
  • disqualified (CGO + no driver)
• github.com/mattn/go-sqlite3, a CGO-based solution.
  • disqualified (CGO, our current module)
• modernc.org/sqlite, a pure Go solution. This is a newer library, based on the SQLite C code re-written in Go.
  • a potential option
• github.com/ncruces/go-sqlite3, a pure Go solution based on WASM.
  • potential option, though the WASM runtime dependency raises questions especially around performance
• github.com/cvilsmeier/sqinn-go, a solution without CGO. It uses github.com/cvilsmeier/sqinn to access SQLite database files.
  • disqualified (no driver)
• github.com/zombiezen/go-sqlite, a rewrite of the crawshaw driver, using the modernc libraries. This is not a database/sql driver.
  • disqualified (no driver)

So, we're left with effectively 3 options:

• modernc.org/sqlite
• github.com/glebarez/go-sqlite
• github.com/ncruces/go-sqlite3

IMO it's worth experimenting with these three, starting with modernc.org/sqlite.