add "Analyze" group to ContextMenuExtension

Summary:
This patch adds new group to ContextMenuExtension for analyzer plugins. Current versions of "kdev-cppcheck" and "clang-tidy" plugins move theirs actions to common "ExtensionGroup" which produce ugly random order and leads to "clogging" this group when many analyzers plugins are enabled.

New version adds "Analyze with" submenu to context for editor and project items.

Reviewers: kfunk, KDevelop

Reviewed By: kfunk, KDevelop

Subscribers: kfunk, coliveira, kdevelop-devel

Differential Revision: https://phabricator.kde.org/D3013