Add and configure ESLint and update configuration for Prettier (#617)

* Add ESLint, update Prettier

* Update docs

* Update tests

* Update licenses

* Fix review points

src/cache-distributions/pip-cache.ts

@@ -15,7 +15,7 @@ class PipCache extends CacheDistributor {
 
   constructor(
     private pythonVersion: string,
-    cacheDependencyPath: string = '**/requirements.txt'
+    cacheDependencyPath = '**/requirements.txt'
   ) {
     super('pip', cacheDependencyPath);
   }