[feat] adding vpcref to linodemachine

[komer3]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

TODOs:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

[codecov]

Codecov Report

Attention: Patch coverage is 86.00000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 64.94%. Comparing base (8684d43) to head (4923e0d).

Files with missing lines	Patch %	Lines
controller/linodemachine_controller.go	81.81%	4 Missing and 2 partials ⚠️
controller/linodemachine_controller_helpers.go	94.11%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #553      +/-   ##
==========================================
+ Coverage   64.76%   64.94%   +0.17%     
==========================================
  Files          79       79              
  Lines        5583     5625      +42     
==========================================
+ Hits         3616     3653      +37     
- Misses       1694     1697       +3     
- Partials      273      275       +2     

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