Add pidfile test

[YJDoc2]

This adds the pidfile test : which , for some reason, was failing for oci-runtime-tools in github actions. Now that I have implemented this, and it works, I am worried I have implemented it wrong 😄 😅
This test works on both local setup and GitHub actions.
Please take a look @utam0k @yihuaf

[codecov-commenter]

Codecov Report

Merging #379 (3cc47a7) into main (d907c13) will decrease coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #379      +/-   ##
==========================================
- Coverage   76.52%   76.47%   -0.06%     
==========================================
  Files          52       52              
  Lines        8210     8311     +101     
==========================================
+ Hits         6283     6356      +73     
- Misses       1927     1955      +28     

[utam0k]

In runtime-tools, it does createruningstopped, but I feel this is enough for us since it seems to have nothing to do with the pid file.
https://github.com/opencontainers/runtime-tools/blob/59cdde06764be8d761db120664020f0415f36045/validation/pidfile/pidfile.go#L59-L64

[utam0k]

LGTM

[YJDoc2]

Yes, I felt that checking it would take extra state checks which should not be relevant in an option of create command anyways, so I only added check for validating if container is created, and then the pid file.

In runtime-tools, it does create running stopped, but I feel this is enough for us since it seems to have nothing to do with the pid file.