Enable additional BUILD_FLAGS for fips

[Vincent056]

What type of PR is this?

/kind feature

-->

What this PR does / why we need it:

Adding an env variable to the Make file so we can use to pass extra build arg to enable features like FIPS.
ex. BUILD_FLAGS="-tags strictfipsruntime"

Which issue(s) this PR fixes:

None

Does this PR have test?

N/A

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Adding an env variable to the Make file so we can use to pass extra build arg to enable features like FIPS.

[codecov-commenter]

Codecov Report

Merging #1945 (b34274c) into main (edb34ac) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1945   +/-   ##
=======================================
  Coverage   49.25%   49.25%           
=======================================
  Files          72       72           
  Lines        7037     7037           
=======================================
  Hits         3466     3466           
  Misses       3437     3437           
  Partials      134      134           

[saschagrunert]

@Vincent056 may I ask you to rebase please?

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: saschagrunert, Vincent056

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