[Explorer] Add footer to explorer pages

[ukorvl]

Requirements

We would like to have a footer on every explorer page. Figma template.
For the implementation of footer use React jsx and styling with react-styletron. For typography use Typography components provided by @nilfoundation/ui-kit.

Ensure that mobile and tablet views are rendered correctly.

DOD

Footer is added to every page in explorer - main page and all internal pages - transaction, block and address. And it renders correctly on all 3 screen types.

[Verifieddanny]

Mind if I take this issue?

[emarc99]

I would love to be assigned to do this ser!