* ProfileImageBytes for EnsureBotOptions
* leverage plugintest.NewAPI
* fix linting
* add UpdateUserRoles to plugin api
* MM-57018: support reattaching plugins
Expose a local-only API for reattaching plugins: instead of the server starting and managing the process itself, allow the plugin to be launched externally (eg within a unit test) and reattach to an existing server instance to provide the unit test with a fully functional RPC API, sidestepping the need for mocking the plugin API in most cases.
In the future, this may become the basis for running plugins in a sidecar container.
Fixes: https://mattermost.atlassian.net/browse/MM-57018
* drop unused supervisor.pid
* factor out checkMinServerVersion
* factor out startPluginServer
* restore missing setPluginState on successful reattach
* avoid passing around a stale registeredPlugin
* inline initializePluginImplementation
* have IsValid return an error
* explicitly close rpcClient
In the case of reattached plugins, the Unix socket won't necessarily disappear leaving the muxBrokers blocked indefinitely. And `Kill()` doesn't do anything if there's no process being managed.
* explicitly detachPlugin
* emphasize gRPC not being supported
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Co-authored-by: Mattermost Build <build@mattermost.com>