[VSCode] Add ="" to built-in tag helper completion

[marcusturewicz]

Describe the solution you'd like

For IntelliSense completion on built in tag helpers (asp-action, asp-page etc), it would be nice for the completion to include the equals and quotation characters, like the HTML attributes do. See GIF below.

Additional context

I'm using VS Code, not sure if this already works in full VS or not.

[marcusturewicz]

Happy to have a crack at this, if pointed in the right direction :)

[mkArtakMSFT]

Thanks for your suggestion, @marcusturewicz. Given the fragility of this area we think this one is a better fit for the team to handle.

[TanayParikh]

Current Implementation:

We had previously supported ="|" quotes when you press =, but that functionality was removed to avoid issues like:

• <button @attrib| press = -> <button @attributes="=|"
• @onkey| press : -> @onkeydown=":|"
• Taghelper attribute <form ap-anti press ` -><form asp-antiforgery=" |"`
• Taghelper attribute <form ap-ar press = -> <form asp-area="=|"

The LSP spec doesn't currently allow different CompletionItem.InsertText snippets for different commit characters. However, for the commit characters : and =, we need snippet texts of :| and ="|" respectively.