* dvc: get rid of is_walking_tree
No longer needed. Some applications of `isinstance()` will be refactored
in the future, as trees will just provide the needed functionality.
* dvc: move GitTree to dvc/tree/
* dvc: rename *RemoteTree to *Tree
* remote: move constants into trees
* remote: replace Remote() Cache() helper functions
* output: update for remote changes
* cache/data_cloud: update for remote changes
* dependency: update for remote changes
* stage: update for remote changes
* remote: move remaining non-index methods into tree
* tests: update remote unit tests
* remote: LocalCache needs to lock remote index, not cache index
* fix bugs from moved PARAM_CHECKSUM/PARAM_RELPATH
* tests: repo tree open needs state context
* remote: make Remote.gc a class method
* operates on obj.tree, so that GC can be done with both remote and
cache instances
* bug fixes
* tests: update test_data_cloud
* bug fixes
* tests: update func tests
* remote: move upload()/download() into tree
* remote: move path_info/path_cls into tree
* remote.azure: finish moving methods into tree
* remote.gs: finish moving methods into tree
* remote.hdfs: finish moving methods to tree
* remote.http: finish moving methods into tree
* remote.oss: finish moving methods into tree
* remote.s3: finish moving methods into tree
* remote.ssh: finish moving methods into tree
* remote.gdrive: finish moving methods into tree
* tests: update remote unit tests
* tests: update func tests
* remote: use walk_files() for all remotes
* list_cache_paths() now uses tree.walk_files() for all remotes except
local/ssh
* fix DS warnings
* bugfixes
* remote: Optimize traverse/no_traverse behavior
- estimate remote file count by fetching a single parent cache dir, then
determine whether or not to use no_traverse method for checking
remainder of cache entries in `cache_exists`
- thread requests when traversing full remote file lists (by fetching
one parent cache dir per thread)
* Use arbitrary prefix length for traverse remote cache queries
- default to 3
- for remotes that only support per-directory query use 2 (gdrive, hdfs)
* Add unit tests for new traverse/no_traverse behavior
* Fix deepsource warning
* Fix review issues
* fix CI
* Fix review issues
* obsolete no_traverse config option
- remove RemoteBASE.DEFAULT_NO_TRAVERSE and replace it with
RemoteBASE.CAN_TRAVERSE (True for all remotes except http)
* review issues - use 'object exists' instead of 'no_traverse'
* fix obsolete no_traverse test issues
* fix SSHMocked func tests