warn instead of forcing ESM interoperability

[huafu]

To allow the required override of module ts config value, the esModuleInterop is set to true. But that has been done in all the cases.

For more flexibility, only allowSyntheticDefaultExports is set to true in the case where module is something else than commonjs AND esModuleInterop is not set to true. Also in that case a diagnostic is reported which by default would fail the compilation (but can be bypassed using the diagnostic filtering system).

This also means that user can stick to deprecated/not standardised version of import if they want.

This fixes #737

[coveralls]

Pull Request Test Coverage Report for Build 1863

• 25 of 25 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.9%) to 90.765%

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Totals
Change from base Build 1862:	0.9%
Covered Lines:	974
Relevant Lines:	1023

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💛 - Coveralls

[GeeWee]

approving with no check