Fix LSP tooltips that are generated as markdown from doc comments

[Youssef1313]

Few lines above this, there is:

                if (!isInCodeBlock)
                    text = text.Replace(" ", " ");

This doesn't feel correct. See the following test:

https://github.com/dibarbet/roslyn/blob/0ef88b0a686892546b57e721ba65738872bf928d/src/Features/LanguageServer/ProtocolUnitTests/Hover/HoverTests.cs#L195

@sharwell Do you agree here? Do you want me to fix LSP in this PR or make that a separate PR? (I prefer LSP work to be separate - but no objection doing it in this PR)

cc: @dibarbet

_Originally posted by @Youssef1313 in https://github.com/dotnet/roslyn/pull/53140#discussion_r630828905_

[Youssef1313]

• <c> should use single backticks, as currently done. BUT, <code> should use code block (triple backticks - probably without a language identifier).
• Spaces should be normalized, except in <code>.
• New lines should be removed if it's between <c> and </c> - but certainly not when it's between <code> and </code>.
• Usage of   shouldn't be needed.

[dibarbet]

Markdown ignores normal leading spaces, so the following written in markdown

Exceptions:
    XYZ

renders as the below Exceptions: XYZ

  ensures the whitespace formatting is kept, for example the following markdown

Exceptions:
    XYZ

renders as this

Exceptions:     XYZ

If you have a better method to ensure the whitespace formatting is kept in markdown I'm all ears. I tried a couple things (<pre>, unicode em space), but this was the only method that worked consistently for me with vscode's markdown renderer

[Youssef1313]

@dibarbet Alright, for this case it looks like it's needed. However, in other places (middle of words) the extra spaces should usually be trimmed. This is done intentionally in VS IntelliSense:

https://github.com/dotnet/roslyn/blob/acf3e276f7d7330274ea537a8b4887b4e2e7f544/src/Features/Core/Portable/DocumentationComments/AbstractDocumentationCommentFormattingService.cs#L550

For example:

<summary>Text    with         many           spaces</summary>

should render as Text with many spaces. Spaces should be normalized even in <c>. The only place it shouldn't be normalized is in <code>

[dibarbet]

Ah interesting! Perhaps the the   should only apply to lines with leading space outside of fences. Markdown would automatically trim spaces elsewhere even inside these code fences, but not in

 these      code      fences

which sounds like the behavior we want.

[dibarbet]

Let me know if you wanted to work on this issue, otherwise I'll assign it to myself to fix.

[Youssef1313]

@dibarbet I'll take a look after https://github.com/dotnet/roslyn/pull/53140 goes in (this PR adds TaggedTextStyle.InlineCode which would be needed to differentiate <code> and <c>.

[sharwell]

Markdown ignores normal leading spaces, so the following written in markdown

Exceptions:
    XYZ

renders as the below Exceptions: XYZ

...

If you have a better method to ensure the whitespace formatting is kept in markdown I'm all ears. ...

The rendering without leading whitespace is the correct rendering, so there is no need to try and add spaces.

[dibarbet]

@sharwell at least in 16.9, it shows with indentation which is what I was going off of

[sharwell]

I would use headings in markdown instead:

### Returns

something

### Exceptions

`NullReferenceException`

[dibarbet]

Hmm, that's a good idea. Works for me!