As part of the PR, it also fixes:
 - Removes button aliases
 - Unifies the keys in the object returned by getAllToolboxButtons and the button keys
 - Makes sure that the number of buttons displayed are always the same as the number of buttons specified in the thresholds and removes the exception for not filling up the main toolbar with buttons from overflow menu when reactions button is disabled.
 - Introduces a priority for buttons that will be used to fill empty spaces in the main toolbar.