Specify page actions

[lens0021]

It will be possible since MediaWiki 1.38.

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Gadgets/+/747112:

Allow specifying page actions ('view', 'edit', 'history', etc) in gadget definitions. If specified, the gadget is run only on the given
page action(s).

This is especially useful for default gadgets like RefToolbar1 and TextReactions2 that only need to be loaded while editing.