Experimental Mount Command

[tri-adam]

Add experimental mount command, which attempts to mount the primary system partition of a SIF image. At the moment, only SquashFS partitions are supported via squashfuse. Add OptWithExperimental to enable/disable hidden, experimental commands in siftool.

Closes #191

[codecov-commenter]

Codecov Report

Merging #195 (389f08f) into master (d7a38b5) will decrease coverage by 0.18%.
The diff coverage is 58.06%.

@@            Coverage Diff             @@
##           master     #195      +/-   ##
==========================================
- Coverage   76.46%   76.28%   -0.19%     
==========================================
  Files          28       30       +2     
  Lines        2503     2534      +31     
==========================================
+ Hits         1914     1933      +19     
- Misses        450      461      +11     
- Partials      139      140       +1     

Impacted Files	Coverage Δ
internal/app/siftool/mount.go	0.00% <0.00%> (ø)
internal/app/siftool/app.go	65.21% <16.66%> (-17.14%)	⬇️
pkg/siftool/mount.go	72.72% <72.72%> (ø)
pkg/siftool/siftool.go	92.30% <100.00%> (+5.64%)	⬆️

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[dtrudg]

LGTM. Confirmed working on Fedora 35