[Release 8] Update title with uploaded file name

[ferishili]

This PR fixes #171,

Description

please refer to https://github.com/opencast-ilias/OpenCast/issues/171#issuecomment-1611475381

How it works

• FileInputMutationObserver js class is introduced to add an observer to the file input container.
• By registering the observer on drop and click event (in capturing mode) on the file input div container, we can recognize when the dz-name span is appended to the container which contains the filename.
• FileInputMutationObserver is capable of invoking external callback from outside, that means the function you need to perform can be written in the withAdditionalOnLoadCode, by passing an array of arbitrary callables to the init method.
• The validation message (when required inputs are empty) is also updated and uses custom string, accessible in langs with id of msg_empty_required_field

[dagraf]

I tested this PR and everything worked as expected. Thanks!

@ferishili: Can you please prepare this PR for merging and when done contact @chfsx? Thx!

[ferishili]

@chfsx, PR is ready. Thanks in advance.