SQLite extension loading via sqlx.toml for CLI and query macros

[djarb]

fixes issue #3330 by allowing the query checking macros to load SQLite extensions specified in sqlx.toml.

Related to that, also allows the CLI to load the SQLite extensions specified in sqlx.toml when running migrations

[abonander]

I'm very keen in landing this, but besides fixing the build, it does also need some sort of test to prove that it works, and ideally a compile-checked example that shows how to use it. In #3383 I realized I could take out two birds with one stone by adding some example projects showing off the new configuration. I'd suggest doing the same.

[abonander]

(I'm just now realizing the build failures are from #3383 itself so disregard that.)

[djarb]

I'll be happy to add an example, but there's a complication: to demonstrate this functionality, it's necessary to load a SQLite extension, and that requires that the example is dependent on having that extension installed. Are you okay with having an example that has a third-party dependency which is not shipped with SQLx? If so, what is your preference for how I structure that?

[abonander]

Our CI already downloads an extension from https://github.com/nalgeon/sqlean/ for testing: https://github.com/launchbadge/sqlx/blob/65229f7ff91ecd38be7c10fb61ff3e05bedabe87/.github/workflows/sqlx.yml#L125

One thing is that for Unix platforms, you need to show the user either how to set LD_LIBRARY_PATH or to specify a relative path to the extension.

[djarb]

Is there anything further that you need from me to get this merged?

[djarb]

Hello? Just checking in. I'd really appreciate it if this could be merged, or if you could let me know what I need to do to get it to that point.

[djarb]

• Updated the pull request to apply to the current version of the branch.
• The requested example is in place. It has been for months, but I just realized I never explicitly said so.
• To run the example use ./x.py -p sqlite/extension in the examples/ directory.
• A couple of minor, unrelated bug fixes that were necessary in order to be able to run cargo check and the example with the current sqlx-toml version

[abonander]

@djarb this got closed because I merged and deleted the sqlx-toml branch. Please rebase against main and open a new PR.