Some highlights:
- [task] added support for VS Code task contribution points: `taskDefinitions`, `problemMatchers`, and `problemPatterns`
- [plugin] added support of debug activation events [#5645](https://github.com/theia-ide/theia/pull/5645)
Breaking changes (so far):
- [plugin] fixed typo in 'HostedInstanceState' enum from RUNNNING to RUNNING in `plugin-dev` extension
- [plugin] removed member `processOptions` from `AbstractHostedInstanceManager` as it is not initialized or used
- [plugin] added basic support of activation events [#5622](https://github.com/theia-ide/theia/pull/5622)
- HostedPluginSupport is refactored to support multiple `PluginManagerExt` properly
VS Code extensions compatibility, as Theia plugins.