docs/settings: include enum and enum descriptions

Enum and EnumDescriptions/MarkdownEnumDescriptions carry useful information, especially in gopls analysis and codelenses settings. This CL makes generate.go include the info in the settings.md.

Following Rebecca's suggestion from https://go-review.googlesource.com/c/vscode-go/+/283432 we now manually map map[string]interface{} to Property whenever possible, and use writeProperty for both the Detailed list section and the Gopls setting section.

And, this CL also improves the default value display when it has nested objects.  For example, go.delveConfig property's default value.

gocommentToMarkdown is a hack to work around issues that occur when gopls' markdown-style strings are embedded inside tables.

Change-Id: I07434cd58c1b12778a5b980c69e3d4d083deaeb7
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/284936
Trust: Hyang-Ah Hana Kim <[email protected]>
Run-TryBot: Hyang-Ah Hana Kim <[email protected]>
TryBot-Result: kokoro <[email protected]>
Reviewed-by: Rebecca Stambler <[email protected]>