set securityContext for Pods and containers

[AshleyDumaine]

This explicitly sets the securityContext on the Pods and containers and tries to restrict permissions where possible for privileged containers. Specifically, the csi-linode-plugin container needed to be allowed due to the Bidirectional volume mount propagation requirement but the other containers were set to not allow privileged permissions.

General:

• Have you removed all sensitive information, including but not limited to access keys and passwords?
• Have you checked to ensure there aren't other open or closed Pull Requests for the same bug/feature/question?

Pull Request Guidelines:

1. Does your submission pass tests?
2. Have you added tests?
3. Are you addressing a single feature in this PR?
4. Are your commits atomic, addressing one change per commit?
5. Are you following the conventions of the language?
6. Have you saved your large formatting changes for a different PR, so we can focus on your work?
7. Have you explained your rationale for why this feature is needed?
8. Have you linked your PR to an open issue

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.11%. Comparing base (12b1643) to head (9f1b796).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #363      +/-   ##
==========================================
+ Coverage   72.98%   73.11%   +0.12%     
==========================================
  Files          23       23              
  Lines        2636     2648      +12     
==========================================
+ Hits         1924     1936      +12     
  Misses        585      585              
  Partials      127      127              

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unresolved comment