Disconnect the tie between the Content tab filter button and the Store tab filter button

[gynt]

Currently they are tied together, i.e. the filter being on filters both in the Content tab and the Store tab, but the filter button is only displayed in the Content tab. This is confusing.

There are two solutions:

• Add the same button in the Store tab. The Store tab would then have multiple filter buttons, that might be confusing too.
• Add a separate button in the Store tab. The Store tab would still have multiple filter buttons, but we could call the current one "Online only view" with an internet symbol, and the other button the filter button that hides the modules.

I prefer option 2