feat: add emitIsolatedDts support

[jbedard]

Add experimental support for the jsc.experimental.emitIsolatedDts feature to output .d.ts instead of .js.

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Changes are visible to end-users: no

Test plan

• Covered by existing test cases
• New test cases added

[jbedard]

I think we're blocked for now on https://github.com/swc-project/swc/issues/9512 if I'm understanding correctly. The way we invoke the cli using --out-file doesn't work with the swc cli atm.