feat: add get default provider roles api

[Chief-Rishab]

• Requires https://github.com/raystack/proton/pull/322

[coveralls]

Pull Request Test Coverage Report for Build 7109527714

• 0 of 132 (0.0%) changed or added relevant lines in 11 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.8%) to 72.993%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
plugins/providers/dataplex/provider.go	0	3	0.0%
plugins/providers/gcloudiam/provider.go	0	3	0.0%
plugins/providers/noop/provider.go	0	3	0.0%
plugins/providers/tableau/provider.go	0	3	0.0%
core/provider/service.go	0	6	0.0%
api/handler/v1beta1/provider.go	0	8	0.0%
plugins/providers/grafana/provider.go	0	9	0.0%
plugins/providers/gcs/provider.go	0	17	0.0%
plugins/providers/bigquery/provider.go	0	22	0.0%
plugins/providers/metabase/provider.go	0	26	0.0%
<!--	Total:	0	132	0.0%	-->

Totals
Change from base Build 7069016607:	-0.8%
Covered Lines:	8673
Relevant Lines:	11882

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💛 - Coveralls