Make InputMethodInfo#isEncryptionAware() strict.

This is a follow up CL to the previous CL [1], which unintentionally
relied on whether the entire application rather than the
InputMethodService is marked to be encryption-aware.  This wasn't
obvious because right now LatinIME is entirely marked to be
encryption-aware, which probably needs to be reconsidered in subsequent
CLs.

This CL drops "encryptionAware" line from InputMethodInfo#dump() as it
is redundant.  The same information is already dumped in the
'ServiceInfo' section.

 [1] Icf921fe3661eccf4a589b08b616d05decc561356
     69811a98

Bug: 26279466
Change-Id: I6cea5fe5731f4a6a64ea722b854b99c5154a15ae