[embedlite-components] Add EmbedLiteWebrtcUI component. JB#53942

See merge request !120

In addition to "camera" and "microphone" permissions, the MediaManager
uses one more id "MediaManagerVideo", and does not grant permission to
use camera unless the principal has "MediaManagerVideo" allowed. Add
this permission for one shot each time the camera is requested.

The EmbedLiteWebrtcUI component processes getUserMedia:* messages from
the gecko engine and binds them to the UI.

[embedlite-components] Remove "embedui:vkbOpenCompositionMetrics" handler. Contributes to JB#51962

See merge request !128

[embedlite-components] Remove message listener if filepicker was cancelled. Contributes to JB#53949

See merge request !130

The FilePicker.js handle messages for filepickerresponse,
there is no cancelling if the aData is empty.
Should to remove message listener if data is empty and call returnCancell for nsIFilePicker.

Set history item triggering principal to system

See merge request !127

[embedlite-components] Set history item triggering principal to system. Fixes JB#54249 OMP#JOLLA-142

For security reasons the triggering principal of a link is used to
determine whether it can be loaded or not. For example local files can't
be opened by a null triggering principal.

Since history items restored after a restart were given a null
triggering principal, this was preventing local files being loaded from
the history (e.g. using the back/forward buttons) after a restart.

This change sets the triggering principal for restored history items to
the system principal. History items are loaded with the
INTERNAL_LOAD_FLAGS_INHERIT_PRINCIPAL flag unset. The principal for the
loaded file is therefore based on the file origin, rather than the
triggering principal, so the principal/security of the loaded item will
be unaffected.

More info on principals here:

https://developer.mozilla.org/en-US/docs/Mozilla/Gecko/Script_security

Add a helper for managing logins

See merge request !126

Provides an embedlite mediator for accessing the
@mozilla.org/login-manager;1 capabilties.

Support custom http user agent strings

See merge request !122

Updates the UA override helper to listen for the
"embedliteviewhttpuseragentchanged" notification. If received, future
requests from the same tab will make use of the user agent string
provided with the notification.

[embedlite-components] Stringify none primitive types for runJavaScript. JB#53914 OMP#JOLLA-29

See merge request !125

See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures

Drop obsoleted / unused sync SelectHelper.js

See merge request !123

[embedlite-components] Add API for handling popupblocked events.  Contributes to JB#52731

See merge request !117

Adding ability to handle popup blocked event require extension the ContentPermissionMager.
Popup can't be handled as a request in ContentPermissionPrompt and requires to do it mannualy.
So we have to add ability to create permission for session.

[embedlite-components] Guard runjavascript error handler with callbackId. JB#53914 OMP#JOLLA-29

See merge request !124

[embedlite-components] Listen embedui:runjavascript and reply with...

See merge request !121

[embedlite-components] Listen embedui:runjavascript and reply with embed:runjavascript. JB#53914 OMP#JOLLA-29

Remove clearance of general.useragent.override user pref

See merge request !119

[embedlite-components] Remove clearance of general.useragent.override user pref. Contributes to JB#52428

Clearing the general.useragent.override user pref was a temporary
addition intended to be removed on the next upgrade.

Reverts 82949751

[embedlite-components] Replace notifyObserver with sendAcyncMessage for downloadpicker. Contributes to JB#53798

See merge request !118

[embedlite-components] Replace notifyObserver with sendAcyncMessage for downloadpicker. Contributes to JB#53798

WebView requires handling downloadpicker. It would be easier to control using the active window than globally.
Also need to take care of the missing PREF_BD_USEDOWNLOADDIR.

[embedlite-components] Add downloadpicker API to AppHelperDialog. Contributes to JB#51673

See merge request !111

[embedlite-components] Add each Services.embedlite.sendAsyncMessage behind behind try-catch. Fixes JB#53592

See merge request !115

[embedlite-components] Add each Services.embedlite.sendAsyncMessage behind try-catch. Fixes JB#53592

[embedlite-components] Call showChangeLoginNotification always when updating password. Fixes JB#53604

See merge request !116

[embedlite-components] Call showChangeLoginNotification always when updating password. Fixes JB#53604

This commits also drops unnecessary _showChangeLoginDialog.

[embedlite-components] Make about redirector to work. Fixes JB#53593

See merge request !113