fix: Support creating file with `open_file_nonblock`

[JonathanWoollett-Light]

Changes

Updates the OpenOptions with .create(true) to support creating a file when if it doesn't exist.

Reason

This also brings the functionality inline with the documentation which notes Create and opens a File for writing to it.. This improves usability simplifying setting up the logger.

License Acceptance

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license. For more information on following Developer Certificate of Origin and signing off your commits, please check CONTRIBUTING.md.

PR Checklist

• [x] If a specific issue led to this PR, this PR closes the issue.
• [x] The description of changes is clear and encompassing.
• [x] Any required documentation changes (code and docs) are included in this PR.
• [x] API changes follow the Runbook for Firecracker API changes.
• [x] User-facing changes are mentioned in CHANGELOG.md.
• [x] All added/changed functionality is tested.
• [x] New TODOs link to an issue.
• [x] Commits meet contribution quality standards.

---

• [x] This functionality cannot be added in rust-vmm.

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.01% :warning:

Comparison is base (9c51dc6) 82.65% compared to head (cd11fe9) 82.65%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4028      +/-   ##
==========================================
- Coverage   82.65%   82.65%   -0.01%     
==========================================
  Files         221      221              
  Lines       28169    28170       +1     
==========================================
  Hits        23283    23283              
- Misses       4886     4887       +1     

Flag	Coverage Δ
4.14-c7g.metal	78.09% <100.00%> (-0.01%)	:arrow_down:
4.14-m5d.metal	79.88% <100.00%> (-0.01%)	:arrow_down:
4.14-m6a.metal	79.02% <100.00%> (-0.01%)	:arrow_down:
4.14-m6g.metal	78.10% <100.00%> (-0.01%)	:arrow_down:
4.14-m6i.metal	79.88% <100.00%> (-0.01%)	:arrow_down:
5.10-c7g.metal	81.04% <100.00%> (-0.01%)	:arrow_down:
5.10-m5d.metal	82.57% <100.00%> (-0.01%)	:arrow_down:
5.10-m6a.metal	81.81% <100.00%> (+<0.01%)	:arrow_up:
5.10-m6g.metal	81.04% <100.00%> (-0.01%)	:arrow_down:
5.10-m6i.metal	82.57% <100.00%> (+<0.01%)	:arrow_up:
6.1-c7g.metal	81.04% <100.00%> (+<0.01%)	:arrow_up:
6.1-m5d.metal	82.57% <100.00%> (-0.01%)	:arrow_down:
6.1-m6a.metal	81.81% <100.00%> (-0.01%)	:arrow_down:
6.1-m6g.metal	81.04% <100.00%> (-0.01%)	:arrow_down:
6.1-m6i.metal	82.57% <100.00%> (+<0.01%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
src/vmm/src/vmm_config/logger.rs	89.23% <ø> (-1.54%)	:arrow_down:
src/vmm/src/vmm_config/metrics.rs	90.00% <ø> (ø)
src/vmm/src/vmm_config/mod.rs	70.58% <100.00%> (+0.43%)	:arrow_up:

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