feat: explorer panel styles

[sehyod]

This updates the design for the explorer panel

Closes #372

[codecov]

Codecov Report

Merging #435 (5658002) into main (5d3e1c5) will increase coverage by 0.09%.
Report is 2 commits behind head on main.
The diff coverage is 87.91%.

@@            Coverage Diff             @@
##             main     #435      +/-   ##
==========================================
+ Coverage   77.69%   77.78%   +0.09%     
==========================================
  Files         190      188       -2     
  Lines       11570    11527      -43     
  Branches     1115     1116       +1     
==========================================
- Hits         8989     8966      -23     
+ Misses       2565     2546      -19     
+ Partials       16       15       -1     

Files Changed	Coverage Δ
src/application/sidebar/ExplorerPanel.tsx	0.00% <0.00%> (ø)
src/atoms/projectState.ts	33.62% <ø> (-0.57%)	⬇️
src/components/icons.tsx	64.70% <85.71%> (-10.30%)	⬇️
src/application/sidebar/FileExplorer.tsx	99.26% <99.09%> (-0.74%)	⬇️
src/application/sidebar/icons.tsx	53.22% <100.00%> (+53.22%)	⬆️
src/components/PanelWrapper.tsx	100.00% <100.00%> (ø)
src/events.ts	86.66% <100.00%> (+0.22%)	⬆️
src/wrappers/EventsListener.tsx	100.00% <100.00%> (ø)

... and 3 files with indirect coverage changes

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