Add ffi-buffer-reload function to foreign interface.

[jmercouris]

Description

• This allows Nyxt to utilize the renderer for reloading.

Fixes #3325

Checklist:

• [X] Git branch state is mergable.
• [x] Changelog is up to date (via a separate commit).
• [X] New dependencies are accounted for.
• [X] Documentation is up to date.
• [X] Compilation and tests ((asdf:test-system :nyxt/gi-gtk))
  • No new compilation warnings.
  • Tests are sufficient.

[aadcg]

Thanks @jmercouris. I made a slight change to the changelog.

And so the wind blew with an unbeknownst coordinated grace. As if the mouths of all beings of the Earth were summoned to blow in unison.

In other words, it seems that we're roaming in a direction that actually matters.

[aadcg]

For completeness, a note follows.

Commit 83f12c0b63af282d03930a20435d127f7e9ef498 correctly acknowledged that relying on the renderer for reloads is a superior solution. However, it broke reopen-dead-buffer (as in the case of #3329). The aforementioned commit was eventually reverted (in fe825393db6f764ddfbd7a31c06e4880011b2832) to fix the reopen-dead-buffer bug.

What strategy is superior - 83f12c0b63af282d03930a20435d127f7e9ef498 or #3329? I'm convinced that the latter is superior. The renderer will always know best. In the extreme case that the renderer isn't able to reload, then ffi-buffer-reload can always fallback to ffi-buffer-load. Being explicit is better than fitting logic into one of the renderer's method specializations.

CC @jmercouris.