By the time v5 stable will be out, 8 will be EOL (December 2019).

This way we match the Travis CI behavior, and it's inherited by all steps.

Without this, coveralls didn't receive the branch info thus leading to failures when we switched branches.

While important in the past, it has become obsolete, so removing it seems the best solution.

* Allow bundlesize to run for forks too.
* Add name for clone step.
* Add` fail-fast: false`

No more Ruby dependency and most important more than 10 times less build time (at least on Windows)!

Some of the snippets need to be updated later.

* OS X is now macOS

* Update browser-bugs.yml

* Update issue template to break down by bug and template, add support doc to close #23133

* add links from readme for bug and feature templates

* use a trailing slash when possible
* use https when possible
* remove a few redirected links
* consistently use `https://popper.js.org/`
* fix `iconUrl` in nuget files
* change Jekyll Windows guide to the official one