Added cell selection to Calc docs in Android Viewer with a
similar behavior to LOOL wrt. row/column selection.
The user can tap on any header to select whole row/column
or select all by tapping the top left corner of the header.

Change-Id: I34bdbb1aacc5fc0ed9175908936a8a5e6eec4ff4
Reviewed-on: https://gerrit.libreoffice.org/39694Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>