Some CompilerOptions don't work due to deficient `switch-case` in parsinghelpers.go

[srabraham]

I noticed that RewriteRelativeImportExtensions does not work when I use tsgo locally, even though all the code seemed to be in place in this repo. The problem is in a big switch-case in parsinghelpers.go, in which that field (and others) aren't getting converted. I put up a couple of mutually exclusive options as PRs to address this: #839 or #838.

typescript-go/internal/tsoptions/parsinghelpers.go

Lines 143 to 151 in 62c8896

	switch key {
	case "allowJs":
	allOptions.AllowJs = parseTristate(value)
	case "allowSyntheticDefaultImports":
	allOptions.AllowSyntheticDefaultImports = parseTristate(value)
	case "allowNonTsExtensions":
	allOptions.AllowNonTsExtensions = parseTristate(value)
	case "allowUmdGlobalAccess":
	allOptions.AllowUmdGlobalAccess = parseTristate(value)

[srabraham]

FYI @ahejlsberg maybe?