koordlet: export host application cpu and memory usage for prometheus

[yangfeiyu20102011]

Ⅰ. Describe what this PR does

To better monitor the resource usage of the host application, Prometheus metrics have been added.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Describe how to verify it

Ⅳ. Special notes for reviews

V. Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests
• All checks passed in make test

[codecov]

Codecov Report

Attention: Patch coverage is 68.18182% with 7 lines in your changes missing coverage. Please review.

Project coverage is 66.03%. Comparing base (81dfad9) to head (14462c3).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/koordlet/metrics/host_application.go	60.00%	4 Missing and 2 partials ⚠️
...r/collectors/hostapplication/host_app_collector.go	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2259      +/-   ##
==========================================
+ Coverage   66.01%   66.03%   +0.02%     
==========================================
  Files         453      454       +1     
  Lines       53378    53393      +15     
==========================================
+ Hits        35237    35258      +21     
+ Misses      15603    15595       -8     
- Partials     2538     2540       +2     

Flag	Coverage Δ
unittests	66.03% <68.18%> (+0.02%)	⬆️

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[yangfeiyu20102011]

PTAL @saintube
Thanks.

[saintube]

/lgtm
PTAL /cc @zwzhang0107

[j4ckstraw]

可以补充host-application-memory-uasage-with-page-cache #2273

[yangfeiyu20102011]

可以补充host-application-memory-uasage-with-page-cache #2273

We can collect page cache in another PR.
This PR is solely focused on exporting metrics for Prometheus.
cc @j4ckstraw