Fix cache collisions

[huafu]

• Adds a ts-jest digest to the bundle & cache key. The digest depends on all the files included in the bundle (except the digest file itself)
• Fixes possible cache collisions when using a tsConfig file with "extends" #749: possible cache collisions due to the use of input tsconfig instead of resolved one (this would happen if the config was a file with extends: ...
• Improves e2e config extending logic
• Enables compilation caching for unit and e2e in CI now that we depend on the bundle digest
• Ensure the local version of binaries are used within npm scripts

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For reviewers: most of the changes are in tests and test utilities. Only source files changed:

• src/compiler.ts
• src/config/config-set.ts
• src/index.ts
• package.json - ensures local versions of binaries are called within scripts

[coveralls]

Pull Request Test Coverage Report for Build 1883

• 7 of 7 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.4%) to 91.142%

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Totals
Change from base Build 1882:	0.4%
Covered Lines:	971
Relevant Lines:	1016

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💛 - Coveralls

[ahnpnl]

The changes LGTM