NAS-132372 / 25.04 / Add /dev/zvol root for explorer

[RehanY147]

Changes:

Adds option to load zvols alongside datasets by providing two root paths. /dev/zvol alongside /mnt when calling filesystem.listdir endpoint. ix-explorer root property should be set to / for this. Default root for ix-explorer is /mnt

Testing:

Test on the TrueCloud Task Form. The path explorer should show '/' as it's root. When expanded, it should show two children paths. '/mnt' and '/dev/zvol'. When expanded, '/mnt' should show the normal datasets and '/dev/zvol' should show the zvols.

[bugclerk]

Jira URL: https://ixsystems.atlassian.net/browse/NAS-132372

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 82.38%. Comparing base (28145e9) to head (33f1853).
Report is 7 commits behind head on master.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/app/services/filesystem.service.ts	45.45%	6 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #11106    +/-   ##
========================================
  Coverage   82.38%   82.38%            
========================================
  Files        1648     1647     -1     
  Lines       57694    57876   +182     
  Branches     5944     5958    +14     
========================================
+ Hits        47532    47682   +150     
- Misses      10162    10194    +32     

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[undsoft]

We may also want to address the [ENOENT] Directory /dev/zvol does not exist error that may happen if user does not have any zvols.

[undsoft]

let's not abbreviate