Pr/apply filter in overview

[HuntTheSun]

Implementation of #301

Sorry for the one large commit, my IDE autoformatted a bunch of code, making diffs giant and I only realized it too late.
Do you care about atomic commits for review or do you review all changes in one diff anyway?

Changes made:

1. Filter button shown in overview
2. Filter applies in overview (accesses filteredRuns as datasource now)
3. Removed percentage select from overview, moved to global settings
4. moved overview subfilter functions filter.js -> overview.js (it is a filter, but has more to do with overview imo, let me know if I should revert it)
5. minor bugfixes/guards
6. add filter active indicator to filter button

I dont know if you want the filter active dot in the topbar, just drop those commits if you dont,
I just added them since I frequently forgot if I had a filter active during testing.

Heres a sample:
apply_overview_filter.html

I hope it isn't too much of a hassle to review :)
Please take your time and let me know if I should change anything.
Thank you!

[HuntTheSun]

Oh yeah, I forgot to ask:
Should I add a commit for the changed testing browser reference images?