chore: rename remaining spec to intent

[SparkYuan]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

chore: rename remaining spec to intent

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

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

[coveralls]

Pull Request Test Coverage Report for Build 7043433191

• 86 of 103 (83.5%) changed or added relevant lines in 26 files are covered.
• 6 unchanged lines in 4 files lost coverage.
• Overall coverage decreased (-0.04%) to 75.049%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/engine/operation/graph/resource_node.go	0	1	0.0%
pkg/modules/generators/ordered_resources_generator.go	6	7	85.71%
pkg/modules/generators/workload/job_generator.go	2	3	66.67%
pkg/modules/util.go	4	5	80.0%
pkg/cmd/apply/options.go	3	5	60.0%
pkg/engine/operation/diff.go	0	2	0.0%
pkg/cmd/build/util.go	8	11	72.73%
pkg/cmd/preview/options.go	13	16	81.25%
pkg/engine/operation/parser/spec_parser.go	5	8	62.5%

Files with Coverage Reduction	New Missed Lines	%
pkg/engine/operation/parser/spec_parser.go	1	65.85%
pkg/modules/generators/ordered_resources_generator.go	1	90.57%
pkg/modules/util.go	1	70.29%
pkg/engine/operation/parser/parser.go	3	79.27%

Totals
Change from base Build 7028690290:	-0.04%
Covered Lines:	6500
Relevant Lines:	8661

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💛 - Coveralls