Emmet support

  - fix bun in Bem filter
SaveProjectAsTemplateAction: filtering .idea content
IDEA-94641 Save Project As Template: impossible to overwrite the existing template
cleanup, notnull
diagnostics
[vcs] initialize components in the constructor

Otherwise it is not clear whether they can be safely used further without NPE.
[vcs] code style
[vcs] rework "Filter update info by scope" UI in the Settings

* Move everything into separate child configurable.
* Add a checkbox instead of "[None]" combobox value.
* Add "Edit scopes" link.
[vcs] "Filter update info by scope" action fixes

* Remember the filter state in the settings.
* Let it show (but disable) even if filtering is turned off.
* Set action description.
IDEA-99741 Maven system dependencies cause error highlighting
IDEA-100625 Gradle: Throwable at GradleJarManager$2.run()