chore: generate countries.tsx from Go code (#15274)

Closes https://github.com/coder/coder/issues/15074

We have a hard-coded list of countries at
https://github.com/coder/coder/blob/main/site/src/pages/SetupPage/countries.tsx.
This means Go code in coder/coder doesn't have an easy way of utilizing
it.

## Solution
Generate countries.tsx from Go code. Generated by `scripts/apitypings`

scripts/apitypings/main.go

@@ -57,6 +57,7 @@ func main() {
 	}
 
 	_, _ = fmt.Print("// Code generated by 'make site/src/api/typesGenerated.ts'. DO NOT EDIT.\n\n")
+
 	for _, baseDir := range baseDirs {
 		_, _ = fmt.Printf("// The code below is generated from %s.\n\n", strings.TrimPrefix(baseDir, "./"))
 		output, err := Generate(baseDir, external...)