Revert "cleanup: remove pulumi deplendency, use third_party instead (#68)"

[howieyuen]

This reverts commit f36425ff9e354c6cf49d4688bab7120a11725ba4.

The initial aim is to reduce kusion binary size, so remove the pulumi sdk, use third-party instead. However, I found the size is not really reduced a lot, event not 1 MB:

Use 3rd-party, size is 49918992
Use module dependency, size is 50364496
Only reduced 50364496 - 49918992 = 445504, roughly equal to 450 KB

[coveralls]

Pull Request Test Coverage Report for Build 3637580773

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 10 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.1%) to 72.144%

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Files with Coverage Reduction	New Missed Lines	%
pkg/engine/operation/parser/parser.go	3	75.0%
pkg/kusionctl/cmd/apply/options.go	7	70.16%

Totals
Change from base Build 3620276350:	-0.1%
Covered Lines:	4566
Relevant Lines:	6329

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💛 - Coveralls