Fix bug where REPL inputs were compiled as ESM in ESM projects

[cspotcode]

Changed the virtual filename <repl>.ts to <repl>.cts, but only on TS >= 4.5 which is the first version to support cts files. Then added a test.

Fixes #1902
Fixes #1924

[codecov]

Codecov Report

Merging #1959 (8259e9a) into main (ba741fa) will increase coverage by 0.54%.
The diff coverage is 96.15%.

Impacted Files	Coverage Δ
src/repl.ts	84.25% <94.44%> (+4.16%)	⬆️
src/bin.ts	90.16% <100.00%> (+2.87%)	⬆️
src/file-extensions.ts	94.87% <100.00%> (-5.13%)	⬇️
src/child/spawn-child.ts	81.25% <0.00%> (-6.25%)	⬇️
src/configuration.ts	86.71% <0.00%> (+0.42%)	⬆️

[cspotcode]

Failure is because TS 4.2 does not understand .cts file extension. Fix for that is probably change REPL_FILENAME into a fn that accepts TS version number, so can detect if TS >= 4.5.0.

May have to conditionally disable the new "repl executes input as cjs even in esm projects" test on older TS that doesn't understand NodeNext. Test locally first.