Better support for apply functions

[isalkind]

Apply functions could only be updated via the config file and these custom entries where overwritten if changes where made to the accessory through the UI.

These changes where made to allow a separate entry for the topic apply function (still only in config file), but these changes are not overwritten by changes made through the UI.

• pre-process the config on startup to transform the new topic apply entries into the currently accepted form as needed.

• config.schema.json updates to support

• existing custom entries in the config file are not impacted

[arachnetech]

Sounds interesting, but I see you closed the pull request. More work to do first?