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/create-step-between.ts

@@ -0,0 +1,36 @@
+import { getArgValues } from './helpers/get-arg-values';
+import { getExistingStepNums } from './helpers/get-existing-step-nums';
+import { getProjectPath } from './helpers/get-project-path';
+import { padWithLeadingZeros } from './helpers/pad-with-leading-zeros';
+import { createStepFile, getChallengeSeeds, reorderSteps } from './utils';
+
+const allStepsExist = (steps: number[], stepsToFind: number[]) =>
+  stepsToFind.every(num => steps.includes(num));
+
+const projectPath = getProjectPath();
+const args = getArgValues(process.argv);
+
+const start = parseInt(args.start, 10);
+
+if (!Number.isInteger(start) || start < 1) {
+  throw 'Step not created. Start step must be greater than 0.';
+}
+
+const end = start + 1;
+
+const existingSteps = getExistingStepNums(projectPath);
+if (!allStepsExist(existingSteps, [start, end])) {
+  throw `Step not created. Both start step, ${start}, and end step, ${end}, must exist`;
+}
+
+const challengeSeeds = getChallengeSeeds(
+  `${projectPath}step-${padWithLeadingZeros(start)}.md`
+);
+createStepFile({
+  stepNum: start,
+  projectPath,
+  challengeSeeds,
+  stepBetween: true
+});
+console.log(`Sucessfully added step between step #${start} and step #${end}`);
+reorderSteps();