Adding Config Settings for All Configurable Riot Settings

[gary-kim]

List of configuration in Riot: https://github.com/vector-im/riot-web/blob/develop/docs/config.md.

There are separate issues for some of these settings:

• integrations_ui_url, integrations_rest_url, integrations_widgets_url: Allow setting integrations #18
• showLabsSettings, features: Allow Enabling Labs #2

[Thatoo]

It would be great to add https://github.com/vector-im/element-web/blob/develop/docs/jitsi.md too

{
  "jitsi": {
    "preferredDomain": "your.jitsi.example.org"
  }
}

[gary-kim]

@Thatoo We already have Jitsi configurable:

riotchat/src/components/AdminSettings.vue

Lines 121 to 134 in 78eca86

	<SettingsSection
	:title="t('riotchat', 'Jitsi settings')"
	:description="t('riotchat', 'Configure the Jitsi instance that Element will connect to.')"
	>
	<label
	ref="jitsi_preferred_domain"
	for="jitsi_preferred_domain"
	>{{ t('riotchat', 'Custom Jitsi instance (leave blank to use default Element Jitsi server):') }}</label>
	<input
	id="jitsi_preferred_domain"
	v-model="jitsi_preferred_domain"
	type="text"
	@change="updateSetting('jitsi_preferred_domain')"
	>