fix: allow log in testString, restrict test errors

Console logs from testString get reported and test errors are sent to
the dev console (JS).

challenge building is only attempted if there is a build function to do
so.

Various functions have been renamed to better reflect what they do.

client/src/templates/Challenges/utils/build.js

@@ -71,6 +71,11 @@ const buildFunctions = {
   [challengeTypes.backEndProject]: buildBackendChallenge
 };
 
+export function canBuildChallenge(challengeData) {
+  const { challengeType } = challengeData;
+  return buildFunctions.hasOwnProperty(challengeType);
+}
+
 export async function buildChallenge(challengeData) {
   const { challengeType } = challengeData;
   let build = buildFunctions[challengeType];