swap commands to new style

[miniscruff]

Closes #71 ( also removing Afero while I am here )

Check the following

• Keep 100% code coverage
• Be properly formatted
• Documentation changes are included
• Include a change file if expected

Want the new prompt package for this work as well, opening this so I don't forget.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (89dea9b) 100.00% compared to head (8e9ce3f) 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##              main      #466    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           14        14            
  Lines         1740      1857   +117     
==========================================
+ Hits          1740      1857   +117     

Impacted Files	Coverage Δ
cmd/next.go	100.00% <ø> (ø)
cmd/batch.go	100.00% <100.00%> (ø)
cmd/gen.go	100.00% <100.00%> (ø)
cmd/init.go	100.00% <100.00%> (ø)
cmd/latest.go	100.00% <100.00%> (ø)
cmd/merge.go	100.00% <100.00%> (ø)
cmd/new.go	100.00% <100.00%> (ø)
cmd/root.go	100.00% <100.00%> (ø)
core/change.go	100.00% <100.00%> (ø)
core/config.go	100.00% <100.00%> (ø)
... and 2 more

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