* Add backend plugin changes
* Fix totp backend plugin tests
* Fix logical/plugin InvalidateKey test
* Fix plugin catalog CRUD test, fix NoopBackend
* Clean up commented code block
* Fix system backend mount test
* Set plugin_name to omitempty, fix handleMountTable config parsing
* Clean up comments, keep shim connections alive until cleanup
* Include pluginClient, disallow LookupPlugin call from within a plugin
* Add wrapper around backendPluginClient for proper cleanup
* Add logger shim tests
* Add logger, storage, and system shim tests
* Use pointer receivers for system view shim
* Use plugin name if no path is provided on mount
* Enable plugins for auth backends
* Add backend type attribute, move builtin/plugin/package
* Fix merge conflict
* Fix missing plugin name in mount config
* Add integration tests on enabling auth backend plugins
* Remove dependency cycle on mock-plugin
* Add passthrough backend plugin, use logical.BackendType to determine lease generation
* Remove vault package dependency on passthrough package
* Add basic impl test for passthrough plugin
* Incorporate feedback; set b.backend after shims creation on backendPluginServer
* Fix totp plugin test
* Add plugin backends docs
* Fix tests
* Fix builtin/plugin tests
* Remove flatten from PluginRunner fields
* Move mock plugin to logical/plugin, remove totp and passthrough plugins
* Move pluginMap into newPluginClient
* Do not create storage RPC connection on HandleRequest and HandleExistenceCheck
* Change shim logger's Fatal to no-op
* Change BackendType to uint32, match UX backend types
* Change framework.Backend Setup signature
* Add Setup func to logical.Backend interface
* Move OptionallyEnableMlock call into plugin.Serve, update docs and comments
* Remove commented var in plugin package
* RegisterLicense on logical.Backend interface (#3017)
* Add RegisterLicense to logical.Backend interface
* Update RegisterLicense to use callback func on framework.Backend
* Refactor framework.Backend.RegisterLicense
* plugin: Prevent plugin.SystemViewClient.ResponseWrapData from getting JWTs
* plugin: Revert BackendType to remove TypePassthrough and related references
* Fix typo in plugin backends docs
* WIP on invalidate function
* cassandraConnectionProducer has Close()
* Delete database from connections map on successful db.Close()
* Move clear connection into its own func
* Use const for database config path
