Add post-update hook for sbt-java-formatter

[fthomas]

Example PR: scala-steward-org/test-repo-2#73

Closes #2334.

[codecov]

Codecov Report

Merging #2335 (c2b9977) into master (d1f07c4) will increase coverage by 0.01%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #2335      +/-   ##
==========================================
+ Coverage   79.70%   79.71%   +0.01%     
==========================================
  Files         137      137              
  Lines        2390     2406      +16     
  Branches       58       56       -2     
==========================================
+ Hits         1905     1918      +13     
- Misses        485      488       +3     

Impacted Files	Coverage Δ
...rg/scalasteward/core/edit/hooks/HookExecutor.scala	92.85% <66.66%> (-7.15%)	⬇️

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