Fix JavaScript target errors

`Name contains illegal chars that cannot appear in JavaScript identifier.`

I thought about using the `@JsName` annotation here to just rename the test method in JavaScript, but that potentially duplicated the test name. Easier to just replace spaced with underscores, and then remove the backtick escapes.

Author: darronschall

runtime/src/commonTest/kotlin/com/collectiveidea/ktor/IsJsonHelpersKtTest.kt

@@ -9,19 +9,19 @@ import kotlin.test.assertTrue
 
 class IsJsonHelpersKtTest {
     @Test
-    fun `ContentType isJson returns true when missing charset`() {
+    fun contentType_isJson_returns_true_when_missing_charset() {
         val contentType = ContentType.Application.Json
         assertTrue(contentType.isJson())
     }
 
     @Test
-    fun `ContentType isJson returns true when charset present`() {
+    fun contentType_isJson_returns_true_when_charset_present() {
         val contentType = ContentType.Application.Json.withCharset(Charsets.UTF_8)
         assertTrue(contentType.isJson())
     }
 
     @Test
-    fun `ContentType isJson returns false when not explicitly json`() {
+    fun contentType_isJson_returns_false_when_not_explicitly_json() {
         val contentType = ContentType.Application.Any
         assertFalse(contentType.isJson())
     }

runtime/src/commonTest/kotlin/com/collectiveidea/twirp/ErrorResponseTest.kt

@@ -14,7 +14,7 @@ class ErrorResponseTest {
     }
 
     @Test
-    fun `decodes properly with missing meta`() {
+    fun decodes_properly_with_missing_meta() {
         val error = decode("""{"code":"not_found","msg":"not found"}""")
 
         assertEquals(ErrorCode.NotFound, error.code)
@@ -23,15 +23,15 @@ class ErrorResponseTest {
     }
 
     @Test
-    fun `decodes unrecognized enum as enum`() {
+    fun decodes_unrecognized_enum_as_enum() {
         val error = decode("""{"code":"this_is_not_available","msg":"new error code"}""")
 
         assertEquals(ErrorCode.Unknown, error.code)
         assertEquals("new error code", error.msg)
     }
 
     @Test
-    fun `decodes meta with arbitrary values`() {
+    fun decodes_meta_with_arbitrary_values() {
         val error = decode(
             """{
             "code":"canceled",