feat: move internal.kusion.io to api.kusion.io

[SparkYuan]

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 9063899795

Details

• 39 of 89 (43.82%) changed or added relevant lines in 9 files are covered.
• 25 unchanged lines in 4 files lost coverage.
• Overall coverage decreased (-0.2%) to 54.702%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/engine/api/generate/generator/generator.go	0	1	0.0%
pkg/server/manager/stack/util.go	0	1	0.0%
pkg/modules/generators/app_configurations_generator.go	2	4	50.0%
pkg/apis/api.kusion.io/v1/types.go	0	46	0.0%

Files with Coverage Reduction	New Missed Lines	%
pkg/engine/operation/parser/parser.go	3	75.61%
pkg/engine/operation/parser/spec_parser.go	4	56.1%
pkg/apis/api.kusion.io/v1/types.go	8	0.0%
pkg/apis/api.kusion.io/v1/resource.go	10	0.0%

Totals
Change from base Build 9063674741:	-0.2%
Covered Lines:	8790
Relevant Lines:	16069

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💛 - Coveralls

[Liuxingyu1111111]

lgtm