refactor: remove BasePlugin mod

[deryrahman]

Tracker:

• Clean up plugin repo where accepting base plugin
• Remove grpc go-plugin implementation on plugin/v1beta1
• Deprecate base proto endpoint on proton feat(optimus): remove base plugin mod proton#209
• Remove relevant test for base plugin replace it with YamlMod
• Remove BasePlugin and CLIMod on bq2bq feat: bump optimus version to remove commandline mod and base plugin mod transformers#58

[coveralls]

Pull Request Test Coverage Report for Build 3407765430

• 22 of 34 (64.71%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.08%) to 78.559%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
models/plugin.go	15	27	55.56%

Files with Coverage Reduction	New Missed Lines	%
models/plugin.go	1	54.7%

Totals
Change from base Build 3407345732:	-0.08%
Covered Lines:	7980
Relevant Lines:	10158

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💛 - Coveralls

[deryrahman]

Now, the flow of loading plugin will begin on reading yaml plugin first and then binary plugin, since the binary plugin require information eg. plugin name, from yaml.

Later on, we can do packaging the yaml+binary in one release, so that reading the plugin can be done in one shot. @smarch-int

[smarchone]

need to discuss, if plugin options can also be depricated

[smarchone]

LGTM!