[BUGFIX] Move EM tabs to function menu

Changes the tabs in extension manager to a function menu.
The views to manage+get extensions are different from a
user perspective.

Change-Id: I2612667cdb2656fa8954b09ada858581318b3c1d
Fixes: #46931
Releases: 6.0, 6.1
Reviewed-on: https://review.typo3.org/19581
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
[TASK] EM: Modules deserve headlines

Users should know which context is active.
Display context as module headline.

Change-Id: I7e572c019f3d6a290ee699a695c98a5d4ccc6e4e
Fixes: #46934
Releases: 6.0, 6.1
Reviewed-on: https://review.typo3.org/19590
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
[BUGFIX] EM: Add return link to showAllVersions

Extension manager ShowAllVersions view does not deliver
link to return to the TER list. The return link is added.

Change-Id: Iaf266203222416d4c5656d5d52927c0b750b8860
Fixes: #46938
Releases: 6.0, 6.1
Reviewed-on: https://review.typo3.org/19596
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn