Add support for reverting to a user defined epoch

[HerbertJordan]

This PR adds an extra --epoch flag to the heal command of the sonictool to allow users to select the epoch to be reverting to.

This PR covers the basic tooling, and a manual test has been conducted using

go run ./cmd/sonictool --datadir <path-to-data-dir> heal --epoch 61016

where 61016 was 5 epochs before the latest branch. The recovery worked and the node was able to continue syncing after.

[codecov]

Codecov Report

❌ Patch coverage is 62.06897% with 11 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cmd/sonictool/db/heal.go	61.90%	6 Missing and 2 partials ⚠️
cmd/sonictool/app/heal.go	40.00%	2 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (62.06%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Files with missing lines	Coverage Δ
cmd/sonictool/app/cli.go	0.00% <ø> (ø)
cmd/sonictool/app/main.go	100.00% <100.00%> (ø)
cmd/sonictool/app/heal.go	52.17% <40.00%> (-1.68%)	⬇️
cmd/sonictool/db/heal.go	54.23% <61.90%> (-1.84%)	⬇️

... and 9 files with indirect coverage changes

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