No longer require building kvssink to build samples

[stefankiesz]

What was changed?
BUILD_GSTREAMER_PLUGIN is no longer required to be ON for non-kvssink samples to be built. Added new flag BUILD_SAMPLES which defaults to ON to control the building of samples.

NOTE: GStreamer installation is still required for all samples.

Why was it changed?
To allow for the building of non-kvssink samples without the need for building kvssink.

How was it changed?
By removing the sample targets from the BUILD_GSTREAMER_PLUGIN conditional and adding the to a BUILD_SAMPLES conditional.

What testing was done for the changes?
The CI will pass, and testing will be done locally on Mac.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 16.51%. Comparing base (ca558f7) to head (0013fd9).

❗ Current head 0013fd9 differs from pull request most recent head 72a9ede. Consider uploading reports for the commit 72a9ede to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1159      +/-   ##
===========================================
+ Coverage    16.48%   16.51%   +0.03%     
===========================================
  Files           50       50              
  Lines         7019     7022       +3     
===========================================
+ Hits          1157     1160       +3     
  Misses        5862     5862              

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[niyatim23]

I would recommend not turning off building samples for these builds as we wouldn't know if something breaks with the samples. We can exclude samples for the codecov build though to improve our coverage reporting.

[stefankiesz]

Remember to update ReadMe to reflect this