Limit comment tags placement

Documentation comments are recognized only when placed immediately
before entities.

--dumpapi now generates a single block comment when an entity is
hidden/deprecated to comply with the change.

  /* @hide
     @deprecated */
  AIDL entity;

Bug: 177276893
Bug: 177616426
Test: aidl_unittests
Change-Id: I2c00d8e234d1a1ec3fbbcf34f290e0b163d508c0
5 files changed