Enable @typescript-eslint/explicit-function-return-type in /src (#9788)

* Enable `@typescript-eslint/explicit-member-accessibility` on /src

* Prettier

* Enable `@typescript-eslint/explicit-function-return-type` in /src

* Fix types

* tsc strict fixes

* Delint

* Fix test

* Fix bad merge

src/utils/MarkedExecution.ts

@@ -35,14 +35,14 @@ export class MarkedExecution {
     /**
      * Resets the mark without calling the function.
      */
-    public reset() {
+    public reset(): void {
         this.marked = false;
     }
 
     /**
      * Marks the function to be called upon trigger().
      */
-    public mark() {
+    public mark(): void {
         if (!this.marked) this.onMarkCallback?.();
         this.marked = true;
     }
@@ -50,7 +50,7 @@ export class MarkedExecution {
     /**
      * If marked, the function will be called, otherwise this does nothing.
      */
-    public trigger() {
+    public trigger(): void {
         if (!this.marked) return;
         this.reset(); // reset first just in case the fn() causes a trigger()
         this.fn();