DAP: add the ability to hide the #class item for each object

[ono-max]

We can hide the #class item for each object by setting true in hideClassItem.

Closes ruby/vscode-rdbg#37.

Before

After

[amomchilov]

Perhaps there should be a special case for the most common values like:

• true/false/nil
• Integers
• Floats
• Strings

So you can have #class when it's useless, but not have it spam for all "scalar" values

[amomchilov]

I implemented this in https://github.com/ruby/debug/pull/1004/files, with a few improvements:

1. Because of the improvements in Share variable inspection logic between CDP and DAP #1001, the implementation applies to both DAP and CDP.
2. The bug fixes in Share variable inspection logic between CDP and DAP #1001 make the counts correct, so you don't see the disclosure triangles for items that have no members. (e.g. ⋁ a: 1 will now just be a: 1)
3. It still keeps #class when it helps.

I would love to hear your feedback!

[ko1]

discuss on #1004 !