Add text dumpsys section to incidentd

Enable Incidentd to dump any existing dumpsys section in plain text
(as dumpsys.proto), only in eng or userdebug build. This is for a
few dumpsys services that are prohibitively expensive to migrate to
protobuf dumpsys or will undergo a major rewrite (thus render the
previously defined proto completely useless).

Bug: 149816498
Bug: 146085372
Bug: 146086519
Test: $ incident -p EXPLICIT 4000 4001
Change-Id: I0693d9bace0055cfeb63d7c8d48995d57dc0b733