CephFSDocumentsProvider: safer permission checks

CephFSDocumentsProvider: fix java side permission check

CephFSDocumentsProvider: support rstats-via-metadata

defined in aosp and filled by fs-based provider, although nobody reads
it yet

adopt try-with-resources

CephFSDocumentsProvider: make thumbnail failure non-fatal

CephFSExecutor: impl mount mgmt, also bring to fd callback

bump build sdk to 35

for record support

CephFSDocumentsProvider: rework documentId

dedup libcephfs-jni error translation

CephFSDocumentsProvider: refactor permission check

refactor mime types handling

fix various lints

sdk compatibility fixes

bump min due to openProxyFileDescriptor

build: add repo for lint

build: bump agp to 8.6.1

to get rid of riscv64 warning with ndk

build: move to build-tools 34

build: jdk 21, bump gradle and agp for compatibility

build: remove feature toggles for older boost

README: reflect boost build change

jniLibs: remove links

seems not needed with bundled boost