feat: add graceful shutdown

[artek-koltun]

fixes #517

[codecov]

Codecov Report

Merging #599 (1841eca) into main (ef4f782) will decrease coverage by 0.85%.
Report is 33 commits behind head on main.
The diff coverage is 44.66%.

❗ Current head 1841eca differs from pull request most recent head dbad6e2. Consider uploading reports for the commit dbad6e2 to get more accurate results

@@            Coverage Diff             @@
##             main     #599      +/-   ##
==========================================
- Coverage   75.31%   74.46%   -0.85%     
==========================================
  Files          40       41       +1     
  Lines        3622     3725     +103     
==========================================
+ Hits         2728     2774      +46     
- Misses        812      869      +57     
  Partials       82       82              

Files	Coverage Δ
pkg/utils/shutdown.go	44.66% <44.66%> (ø)

[glimchb]

need ore time to review it, so for being slow...