Add function to handle Servers metadata

[jose-caballero]

We are going to use the metadata field to mark certain Servers that require actions.
For example, to mark the Servers that are running an EOL version of the Operating System and when the user was notified about it.

These 2 functions just perform the set and delete steps. The exact content and format of the parameters is responsibility of the workflows code calling them.

Description:

Special Notes:

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Submitter:

Have you (where applicable):

• Added unit tests?
• Checked the latest commit runs on Dev?
• Updated the example config file(s) and README?

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Reviewer

Does this PR:

• Place non-StackStorm code into the lib directory?
• Have unit tests for the action/sensor and lib layers?
• Have clear and obvious action parameter names and descriptions?

[anish-mudaraddi]

these functions are just calling openstacksdk's built-in method .set_server_metadata and .delete_server_metadata and not doing anything else

can't we just call these built-in methods directly in any action/API function that needs to set metadata instead of creating a whole new function that once again verifies that the server exists (slowing down the process by adding an unnecessary API call find_server)

I could see this being useful if you're putting some global validation checks on the properties that is unique to us - but maybe you should just wait until there's a use-case like that before creating these functions? I'm wary of adding more code we need to maintain

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.19%. Comparing base (c774776) to head (9a9a5ef).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

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##             main     #484   +/-   ##
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  Coverage   99.19%   99.19%           
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  Files         112      112           
  Lines        2725     2735   +10     
  Branches      338      338           
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+ Hits         2703     2713   +10     
  Misses         19       19           
  Partials        3        3           

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