snapshotter: add flag to specify nydus-overlayfs path

[katexochen]

This allows installation of multiple nydus-overlayfs versions on the same machine.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 21.73913% with 18 lines in your changes missing coverage. Please review.

Project coverage is 22.07%. Comparing base (4f4dbcd) to head (50a833f). Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
snapshot/mount_option.go	0.00%	10 Missing :warning:
snapshot/snapshot.go	0.00%	6 Missing :warning:
config/config.go	0.00%	1 Missing and 1 partial :warning:

Additional details and impacted files

[](https://app.codecov.io/gh/containerd/nydus-snapshotter/pull/615?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=containerd) ```diff @@ Coverage Diff @@ ## main #615 +/- ## ======================================= Coverage 22.07% 22.07% ======================================= Files 122 122 Lines 10746 10766 +20 ======================================= + Hits 2372 2377 +5 - Misses 8054 8068 +14 - Partials 320 321 +1 ``` | [Files with missing lines](https://app.codecov.io/gh/containerd/nydus-snapshotter/pull/615?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=containerd) | Coverage Δ | | |---|---|---| | [internal/flags/flags.go](https://app.codecov.io/gh/containerd/nydus-snapshotter/pull/615?src=pr&el=tree&filepath=internal%2Fflags%2Fflags.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=containerd#diff-aW50ZXJuYWwvZmxhZ3MvZmxhZ3MuZ28=) | `100.00% <100.00%> (ø)` | | | [config/config.go](https://app.codecov.io/gh/containerd/nydus-snapshotter/pull/615?src=pr&el=tree&filepath=config%2Fconfig.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=containerd#diff-Y29uZmlnL2NvbmZpZy5nbw==) | `36.28% <0.00%> (-0.66%)` | :arrow_down: | | [snapshot/snapshot.go](https://app.codecov.io/gh/containerd/nydus-snapshotter/pull/615?src=pr&el=tree&filepath=snapshot%2Fsnapshot.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=containerd#diff-c25hcHNob3Qvc25hcHNob3QuZ28=) | `0.00% <0.00%> (ø)` | | | [snapshot/mount\_option.go](https://app.codecov.io/gh/containerd/nydus-snapshotter/pull/615?src=pr&el=tree&filepath=snapshot%2Fmount_option.go&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=containerd#diff-c25hcHNob3QvbW91bnRfb3B0aW9uLmdv) | `23.43% <0.00%> (-0.82%)` | :arrow_down: |

[katexochen]

LGTM! Maybe also add the option into misc/snapshotter/config.toml. :)

Thanks, done! :)