Add CodeAction to simplify fully-qualified Component

[ryanbrandenburg]

Summarization

There should be a CodeAction available to simplify the Component name for a fully qualified component tag, either when there is already an @using directive in the file, or if there isn't the code action should insert one.

eg given:

<Microsoft.AspNetCore.Components.Authorization.AuthorizeRouteView />

There should be a code action to "Simplify component tag" which results in the following document:

@using Microsoft.AspNetCore.Components.Authorization
<AuthorizeRouteView />

If the using already exists, it should be left alone. eg given:

@using Microsoft.AspNetCore.Components.Authorization
<Microsoft.AspNetCore.Components.Authorization.AuthorizeRouteView />

Then the "Simplify component tag" code action should result in the following document:

@using Microsoft.AspNetCore.Components.Authorization
<AuthorizeRouteView />

If there are any diagnostics present on the start tag then we shouldn't offer.