[FEATURE] Allow Aloha Buttons to be configured via yaml settings

Change-Id: I2bf521e969878c94c13c91cdb79ababc7f12281f
Resolves: #52330
Reviewed-on: https://review.typo3.org/24198
Reviewed-by: Sebastian Kurfuerst
Tested-by: Sebastian Kurfuerst
[BUGFIX] Image placeholder should not be visible in live

Currently the placeholder image is shown regardless if you are
logged in to the backend or in which workspace.

With this change it is only shown if you have acccess to the
backend and are not on live workspace.

Change-Id: I0789ee8d79ae9580c872b9131278db846328519f
Reviewed-on: https://review.typo3.org/24283
Reviewed-by: Sebastian Kurfuerst
Tested-by: Sebastian Kurfuerst
Reviewed-by: Christian Mueller
Tested-by: Christian Mueller
Merge remote-tracking branch 'origin/master'