quickopen and quickoutline will now show the field icon for field symbols

[hoovercj]

This addresses #21315.

I noticed a few issues:

1. SymbolKind.to and SymbolKind.from didn't map SymbolKind.Field to anything so SymbolKind.Property was used by default
2. There were no classes for field icons except for one high contract mapping that field icons shared with variable icons. I could see that the icon used for variables in that location matched Field_16x.svg, so I operated under the assumption that in the other locations that variable icon classes were defined, field icon classes should be created to point to the same icon

[mention-bot]

@hoovercj, thanks for your PR! By analyzing the history of the files in this pull request, we identified @alexandrudima and @egamma to be potential reviewers.

[msftclas]

@hoovercj,
Thanks for your contribution as a Microsoft full-time employee or intern. You do not need to sign a CLA.
Thanks,
Microsoft Pull Request Bot

[bpasero]

@hoovercj looks good to me but do you have an example where I could verify the fix? When I use TypeScript on an example like this:

class Test {
    public test: string;
}

It looks like public test:string is of kind property and not field.

[hoovercj]

I recently added document symbol support in the HTML language service, so if that version has been pulled in by vscode then you should see html elements as fields/blue bricks in the quick outline. This is how I spotted the discrepancy, I returned SymbolKind.Field but they were appearing with the wrong property wrench icon.

I put together a small extension that you could use to preview the icons. There is a .vsix in the dist/ directory. You open a file named icons.ts and the symbol provider provides one symbol of each type so you can see the icons. Before this change you can see field uses a wrench, after it uses the blue brick.

Otherwise, a quick and dirty way of verifying that the icons are correct is looking at where I modified src/vs/editor/common/modes.ts and modifying the SymbolKind.from/to to always return field, property, or variable and then observe the effects in the document symbols outline.

[bpasero]

Thanks!