Cypress typescript (#13591)

* convert Cypress tests to TypeScript

this work was done by @lunaisnotaboy https://github.com/lunaisnotaboy
for their fork https://github.com/cutiekey/cutiekey/pull/7

I just repacked their changes into a minimal set

* fix call to `window` in cypress tests

this error was spotted thanks to the TypeScript compiler:

```
support/commands.ts:33:12 - error TS2559: Type '(win: any) => void'
has no properties in common with type 'Partial<Loggable &
Timeoutable>'.

33  cy.window(win => {
              ~~~~~~~~

Found 1 error in support/commands.ts:33
```

(again, @lunaisnotaboy did the actual work)

cypress/tsconfig.json

@@ -0,0 +1,8 @@
+{
+	"compilerOptions": {
+		"lib": ["dom", "es5"],
+		"target": "es5",
+		"types": ["cypress", "node"]
+	},
+	"include": ["./**/*.ts"]
+}