[settings] Fix announcement call

[DaVukovic]

Description

This change should fix #15060 as I added a new type and probably OnRefresh could also be used for other scenarios where a home screen reload might be necessary.

Motivation and Context

Fixes the segfault at #15060

How Has This Been Tested?

Runtime tested on Ubuntu 16.04 against latest Kodi master.

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[MartijnKaijser]

Confirmed working

[DaveTBlake]

Glad that the seg fault has been fixed. However the new "VideoLibrary.OnRefresh" notification message also needs to be added to the JSON API, and the schema minor version (middle number) bumped to indicate a change has happened.

@DaVukovic like to raise PR for that please. An addition similar to the following (and inserted below it) is what is needed

xbmc/xbmc/interfaces/json-rpc/schema/notifications.json

Lines 319 to 327 in edc9091

	"VideoLibrary.OnCleanFinished": {
	"type": "notification",
	"description": "The video library has been cleaned.",
	"params": [
	{ "name": "sender", "type": "string", "required": true },
	{ "name": "data", "type": "null", "required": true }
	],
	"returns": null
	},