Update Admin Authentication section to:
- Separate “admin password” and “stream key” terminology
- Emphasize stream key is only for streaming software (RTMP/SRT)
- Note that admin password is used for HTTP Basic auth to `/admin`
Closes#4405.
* add shellcheck to ci
* test ci
* install bash for shellcheck
* set globstar for bash
* cleanup shell scripts
* do not ignore automated hls tests
* rm legacy build script
* update shell scripts
* cleanup ci
* Fix misspell
* cleanup ci
* fail on curl error in ci
