[TASK] Make source language configurable

Resolves: #58049
Releases: 6.2
Change-Id: Ia8541520395204aca569998e4a2461c663f32ae7
Reviewed-on: https://review.typo3.org/29645
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind
[TASK] Remove ExtJS and ExtDirect

Refactoring of Javascript to avoid global
variables. ContainerViewHelper is just a
workaround for #58075

Releases: 6.2
Resolves: #58115

Change-Id: I49dbfb115b93ab785d62c979f31cb9cbf3ba1bcc
Reviewed-on: https://review.typo3.org/29615
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind
Reviewed-by: Nico de Haen
Tested-by: Nico de Haen
[BUGFIX] Trash-button should properly use t3skin

Change-Id: I80d124e6eb099885eaaab10e9056de0eedb91b80
Resolves: #57540
Releases: 6.2
Reviewed-on: https://review.typo3.org/29193
Reviewed-by: Nico de Haen
Tested-by: Nico de Haen
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind