Remove JSON support from APEXd

ApexFile::Open() doesn't fall back to apex_manifest.json for APEX
manifest.

Bug: 143973464
Test: atest CtsStagedInstallHostTestCases
Test: atest ApexTestCases
Change-Id: Ia0fad621806f2dc91caaa3123fdb55fb35f3ab5c
9 files changed