Project spa samples page

[joshsadam]

Description of changes

This PR adds back in the basic project samples table functionality, as well as the merge tool. The PR was getting to big to add in the remainder of the tool sets and will add them on subsequent PRs.

Add 404 page since no longer using server redirect for when an invalid project id is used:

Related issue

Link to the GitHub issue this pull request addresses using the #issuenum format. If it completes an issue, use Fixes #issuenum to automatically close the issue.

Checklist

Things for the developer to confirm they've done before the PR should be accepted:

• ~~[ ] CHANGELOG.md (and UPGRADING.md if necessary) updated with information for new change.~~
• [X] Tests added (or description of how to test) for any new features.
• ~~[ ] User documentation updated for UI or technical changes.~~