MessageList: Introducing "selection mode".

- Long-press an item to go into the selection mode.
- In the selection mode, tap items to toggle selected/non-selected.

This also means:
- No checkboxes any more.
- No context menu any more.

Color scheme hasn't been updated yet, so it looks a bit ugly for now.

Change-Id: I3cb6c45c1dc5461a234c9e9ab9e038c90a9fe8b2
Fix GAL search in EAS 12.1

* We weren't sending the proper protocol version to GAL search, which
  causes errors when using 12.1
* The simple fix is to send the agreed upon protocol version, instead
  of the default (which is 2.5)
* Replace parsing of protocol version with lookup

Bug: 2793588
Change-Id: Ib2a255d8467004ce985d2d688b37066e1e09d78a
Merge commit '91093ee6e8beb200c90e401c96a9c2a1d820bebc' into oxygen_1006

* commit '91093ee6e8beb200c90e401c96a9c2a1d820bebc':
  MessageList: Introducing "selection mode".
Merge commit '663b57daa793c526c69560225c7a073b1abbc3d6' into oxygen_1006

* commit '663b57daa793c526c69560225c7a073b1abbc3d6':
  Fix GAL search in EAS 12.1