refactor: organise TypeScript config and migrate helpers (#44747)

* feat: allow more 1000 steps to be created at once

* refactor: start migrating to typescript

* refactor: delete-step to ts

* refactor: migrated some helpers

* refactor: migrate create-empty-steps

* refactor: migrate create-step-between

* refactor: finish migrating to TS

* refactor: migrate tests

* fix: ensure mock.restore is done after each test

* fix: prevent double-tscing

* fix: repair the tests

* chore: use ts-node for scripts

We don't need the performance boost of incremental compilation and
ts-node is easier to work with

* refactor: consolidate tsconfigs

* refactor: replace gulp

* fix: use ts-node for build-curriculum

* fix: allow ts compilation of config

* feat: create and use create:config script

* fix: add /config to eslint projects

* fix: remove gulp script

tools/challenge-helper-scripts/helpers/get-step-template.ts

@@ -0,0 +1,98 @@
+import ObjectID from 'bson-objectid';
+import { insertErms } from './insert-erms';
+
+// Builds a block
+function getCodeBlock(label: string, content?: string) {
+  return `\`\`\`${label}
+${typeof content !== 'undefined' ? content : ''}
+\`\`\`\n`;
+}
+
+// Builds a section
+function getSeedSection(content: string, label: string) {
+  return content
+    ? `
+
+## --${label}--
+
+${content}`
+    : '';
+}
+
+type StepOptions = {
+  challengeId: ObjectID;
+  challengeSeeds: Record<string, ChallengeSeed>;
+  stepBetween: boolean;
+  stepNum: number;
+};
+
+export interface ChallengeSeed {
+  contents: string;
+  ext: string;
+  editableRegionBoundaries: number[];
+  head?: string;
+  tail?: string;
+}
+
+// Build the base markdown for a step
+function getStepTemplate({
+  challengeId,
+  challengeSeeds,
+  stepBetween,
+  stepNum
+}: StepOptions): string {
+  const seedTexts = Object.values(challengeSeeds)
+    .map(({ contents, ext, editableRegionBoundaries }: ChallengeSeed) => {
+      let fullContents = contents;
+      if (editableRegionBoundaries.length >= 2) {
+        fullContents = insertErms(contents, editableRegionBoundaries);
+      }
+      return getCodeBlock(ext, fullContents);
+    })
+    .join('\n');
+
+  const seedHeads = Object.values(challengeSeeds)
+    .filter(({ head }: ChallengeSeed) => head)
+    .map(({ ext, head }: ChallengeSeed) => getCodeBlock(ext, head))
+    .join('\n');
+
+  const seedTails = Object.values(challengeSeeds)
+    .filter(({ tail }: ChallengeSeed) => tail)
+    .map(({ ext, tail }: ChallengeSeed) => getCodeBlock(ext, tail))
+    .join('\n');
+
+  const descStepNum = stepBetween ? stepNum + 1 : stepNum;
+
+  const stepDescription = `${
+    stepBetween ? 'new ' : ''
+  }step ${descStepNum} instructions`;
+
+  const seedChallengeSection = getSeedSection(seedTexts, 'seed-contents');
+  const seedHeadSection = getSeedSection(seedHeads, 'before-user-code');
+  const seedTailSection = getSeedSection(seedTails, 'after-user-code');
+
+  return (
+    `---
+id: ${challengeId.toString()}
+title: Step ${stepNum}
+challengeType: 0
+dashedName: step-${stepNum}
+---
+
+# --description--
+
+${stepDescription}
+
+# --hints--
+
+Test 1
+
+${getCodeBlock('js')}
+# --seed--` +
+    seedChallengeSection +
+    seedHeadSection +
+    seedTailSection
+  );
+}
+
+export { getStepTemplate };