Irmin pack inspector tool feedback

[clecat]

This issue aims to gather all the feedback/requests that might be done for the tool developed in this pull request once it is merged.

Summary:

• [x] With very large files, show gets laggy as we proceed down the file, probably due to a list, fix that.
• [ ] If files already exist, take advantage of them, don't recompute (ngoguey42).
• [x] Show offsets, not just entry indices (ngoguey42)
• [x] Move to children of node and commit (ngoguey42)
• [x] Prettier print than just Repr.pp for inode and commit. (e.g. decode dict indices, show children hash, child kind) (ngoguey42) (partially done)
• [x] Move one entry at a time, not just per kind (ngoguey42)(was already done at the time)
• [x] Optimize the parsing of the file, to ensure that large files can be properly and consistently processed.
• [ ] Add a progress bar to give the user more input on what is going on (especially on longer files were in can take a minute or more)
• [x] Use the main repository for notty.
• [ ] Add on mouse movement highlighting maybe ?
• [x] Make sure that 4.14 gets supported by notty in order to get rid of the pin

[Ngoguey42]

Some desired QOL enhancement:

• If files already exist, take advantage of them, don't recompute.
• Show offsets, not just entry indices
• Move to children of node and commit
• Prettier print than just Repr.pp for inode and commit. (e.g. decode dict indices, show children hash, child kind)
• Move one entry at a time, not just per kind