chore: enable linting ts files (#6351)

* chore: initial setup for linting ts

* chore: Temporarily disable most of the rules causing problems

* chore: fix autofixable problems.

* chore: ignore the last few files and rules

* chore: fix remaining lint errors

* chore: fix more small lint

* chore: run original rules on js files, new ts rules on ts files

* chore: use jsdoc style return in js files

* chore: add lint fix script

* chore: fix prefer-spread lint

* chore: fix no-invalid-this rule

* chore: fix no-unused-vars

* chore: fix trashcan lint

core/variable_map.ts

@@ -298,7 +298,7 @@ export class VariableMap {
    * @return The variable with the given ID.
    */
   getVariableById(id: string): VariableModel|null {
-    for (const [key, variables] of this.variableMap) {
+    for (const [_key, variables] of this.variableMap) {
       for (const variable of variables) {
         if (variable.getId() === id) {
           return variable;
@@ -365,7 +365,7 @@ export class VariableMap {
   getAllVariableNames(): string[] {
     return Array.from(this.variableMap.values())
         .flat()
-        .map(variable => variable.name);
+        .map((variable) => variable.name);
   }
 
   /**