Allow searching releases by commit sha or commit messages

[kitallis]

Perhaps the all builds page can be repurposed for this. Ideally, this would be in a command-palette type thing. But the first version can be a simple search box to filter.

The all builds page can consequently be renamed to "Find in Tramline"

Changes in Tramline are distributed across the following tables:

1. Commits
2. Pull Requests
3. Release Changelog (commits JSON column)

All these three models are directly associated with the Release model which will be the end result of this search page.