fix: unify doNotSuggest

[p-spacek]

What does this PR do?

related to this conversation redhat-developer/yaml-language-server#911 (comment)

exclude doNotSuggest schema from autocompletion
doNotSuggest was already there but implemented only for the simple object properties.
This PR uses doNotSuggest also for other scenarios: anyOf, values

"anyOf":[
  {
     "$ref": "schema1",
     "doNotSuggest": true
   },
  {
     "$ref": "schema2",
   }
]

PROBLEM

this PR contains also a fix for the test utility testCompletionsFor, there is an issue with checking zero suggested items.
the previous implementation doesn't allow to check 'no result' with expected: { count: 0}
but when I fixed the test utils, the test In comment fails

Options:

• use this PR after the fix of the comments
• if you give me advice on how to check empty results, I can modify this PR (but the comment issue remains)

Is it tested? How?

adds unit tests

[p-spacek]

if you call this method with expected.count === 0 it won't check zero length (assert.equal(list!.items.length, expected.count)

but after this change, it seems that test for test('In comment', ... is not correct

[p-spacek]

@microsoft-github-policy-service agree

[aeschli]

@p-spacek There's a test failure, if you can have a look...

[p-spacek]

@aeschli check the description and code comment please,

Yes, there is an issue with comment implementation. The issue was there before.
The reason why it fails now is because I fixed the utility for testing.
The reason why it didn't fail before is that the utility test incorrectly compared an empty array.

So to be honest, I am not sure how to fix it
I can modify this PR and remove the 'test utility fix' - to hide the comment issue and change my test not to use this test utility
Or I can update the failing comment test to expect two results - instead of 0
I don't dare to fix the comment issue - proper fix.

I am sorry, I shouldn't combine 2 different things together (feature + issue(failing test)), it's confusing now...