Enable search on models' metadata values

[vmjulio]

resolves #396

Description

Extends the fuzzy search capabilities to allow it to search for values for custom metadata.

Checklist

• [x] I have read the contributing guide and understand what's expected of me
• [x] I have signed the CLA
• [x] I have run this code in development and it appears to resolve the stated issue
• [x] I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR
• [x] I have run changie new to create a changelog entry

[vmjulio]

Hey folks, let me know if there's anything I can do to help you reviewing this PR! 🙂

[DanMawdsleyBA]

Is this change complete? Would really welcome this change 😃

[github-actions[bot]]

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[vmjulio]

I was wondering if there's any interesting in merging this one - metadata is quite important and being able to search by key is important! :)

[wartel]

It would be very nice if this feature is added! For us this would open the way to really use the dbt docs the way we would like to use it.