Add context menu on hover

[luke-]

When hover over a file show a "Sandwich/3 Point menu" as access for context menu options.

The options menu when right-clicking is not intiuitively accessible for many users.

[buddh4]

But note, there is no hover on mobile devices.

[spoorun]

But note, there is no hover on mobile devices.

On mobile view, show the sandwich/3 point menu next to each file?

[luke-]

On Mobile we can always show the sandwhich menu?

[yurabakhtin]

@luke- I could implement this only with changes in the core js library humhub.ui.additions.js because there all context menu was hidden on click on any element of document and it was impossible to prevent this action from external module side, so it will works after merging the core PR humhub/humhub#5239.
Changes for this module in PR #128

On Mobile we can always show the sandwhich menu?
I am not sure what css media we can use to detect mobile devices, probably @media (hover: none) {...}, but I see currently the file browser has many columns are hidden on small screens by style class hidden-xxs, so I decided to apply the same rule to display the icon on small screen:

[luke-]

@yurabakhtin ok, great. Then lets postpone this issue until v1.10 when core changes are neccessary. Probably this could also related: #127

[yurabakhtin]

@luke- Min version is updated in commit c228009.

Probably this could also related: #127

I wrote a question but I don't think the task is related, I mean it can be done in separate PR.

[luke-]

@yurabakhtin ok! Then lets create a separate PR.