fix: Add filter icon to help users find filters

[rbreeze]

After sidebar update, it may be confusing where the filters went. This PR does 3 things to improve experience:

1. Sidebar is expanded by default (previously was collapsed by default). This way users who install/upgrade to 2.5 will see the filters the first time they use it and can hide if they choose.
2. When collapsed, instead of showing an arrow there is now a filter icon with a tooltip
3. Improves the spacing/margins of FontAwesome icons in the sidebar; previously, custom sidebar items with FontAwesome icons looked strange.

Before:

After:

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[rbreeze]

i.fa-sign-in-alt was an unused style

[codecov]

Codecov Report

Base: 45.67% // Head: 45.67% // No change to project coverage 👍

Coverage data is based on head (96a48fb) compared to base (9849a17).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #10809   +/-   ##
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  Coverage   45.67%   45.67%           
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  Files         236      236           
  Lines       28697    28697           
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  Hits        13106    13106           
  Misses      13799    13799           
  Partials     1792     1792           

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[alexmt]

I feel it is strange that expand button is changing to filter on some pages. Instead can keep expand button and "collapse" filters into filter icon:

The filter icon would duplicate expand button however it still makes more sense to me.

[alexmt]

Cherry-picked into 2.5