Add support for setting up environment variables for functions using dotenv files.
On deploy, Firebase CLI looks for naive dotenv file (`.env`) file or project-specific ones (`.env.<project id>` or `.env.<project alias>`) files, loads environment variables, and injects them on deployed functions. Environment variable set in project-specific dotenv file wins, and you cannot have both `.<project id>` and `<.project alias>` files.
Environment variables are also loaded up on Firebase Emulators. Emulator will look for `.env` and `.env.local` files and ignore project-specific dotenv files.
We are hiding the feature behind `dotenv` preview flag. We want to get a feeling for the development experience from our users before an official launch + documentations.
Also including a small e2e test for env var support. It's meant to run manually by the Firebase team via command `node scripts/test-functions-env.js`.
* moving small thigns over
* moving small thigns over
* PubSub shceduled functions
* prettier
* prettier
* pr fixes;
* pr fixes;
* use real eventType
* reformat strings, style fixes
* remove unecessary repeated api check
* run prettier
* add tests for deployign scheduled functions, remove innaccurate comment
* clarify comment about eror handling
* changing format to be consistent
* delete now works when cloud scheduler or pubsub api is not enabled, integration tests now use newest firebase functions
* now checks labels to determine whether to delete schedule
* prettier
* changelog
* using chain instead of nested lodash functions
* adds warning comment re changing naming convention
* Clarify comments, standardize tense on changelog
* using varaibles to clarify;
