feat: support google cloud storage as backend

[ffforest]

What type of PR is this?

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

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Additional documentation e.g., design docs, usage docs, etc.:

[coveralls]

Pull Request Test Coverage Report for Build 12479867923

Details

• 82 of 416 (19.71%) changed or added relevant lines in 8 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.5%) to 47.462%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/server/manager/workspace/util.go	0	6	0.0%
pkg/backend/backend.go	0	7	0.0%
pkg/backend/storages/google.go	9	26	34.62%
pkg/apis/api.kusion.io/v1/types.go	0	24	0.0%
pkg/project/storages/google.go	14	43	32.56%
pkg/engine/resource/graph/storages/google.go	0	68	0.0%
pkg/engine/release/storages/google.go	28	106	26.42%
pkg/workspace/storages/google.go	31	136	22.79%

Files with Coverage Reduction	New Missed Lines	%
pkg/engine/operation/parser/parser.go	3	79.27%

Totals
Change from base Build 12479830260:	-0.5%
Covered Lines:	10624
Relevant Lines:	22384

---

💛 - Coveralls

[liu-hm19]

lgtm