Fixes #947: Rebuild search index when needed

[tobiasge]

Related Issue: #947

New Behavior

• Rebuilds search index on startup when models have changed

Contrast to Current Behavior

• Global search is broken because search index entries are missing

Discussion: Benefits and Drawbacks

• When we run this on startup users should not need to worry about the indexes.
• But this makes the start a bit slower

Changes to the Wiki

• None

Proposed Release Note Entry

• Enabled search index rebuilding on start

Double Check

• I have read the comments and followed the PR template.
• I have explained my PR according to the information in the comments.
• My PR targets the develop branch.

[kkthxbye-code]

Any way we can get this out soon-ish?

[cimnine]

Sorry, I thought I approved this weeks ago 🙈