Updates to cache handling and property event handlers

[citizenmatt]

• Fix exception on startup - RIDER-21929 (mistyped the ticket in the commit)
• Mark event handlers as in use if they're declared on a base type - Method marked as never used when used by child classes #922
• Fix highlighting for property used as event handler - gets gutter icon/code insight marker
• Fix find usages for properties used as event handlers

Plus sneaky, unrelated fix to stop the Generate event function dialog selecting all items by default when called from the gutter icon or code code insight marker. See RIDER-22211

[krasnotsvetov]

Do we really need this file?

[citizenmatt]

Possibly not. But I was fed up with it in my "unversioned files". Looking at the file, and the options page that seems to drive it, it looks like it's something that should be shared. And since IntelliJ has no sensible scheme for knowing if a file should be committed or not, I flipped a coin and it ended in.

[krasnotsvetov]

LGTM