While working on JDK-8062373, it has been observed that it would be better to
refactor the method Attr.check to receive a parameter enumeration 'CheckMode'
of the form

enum CheckMode {
   NORMAL,
   NO_TREE_UPDATE,
   NO_INFERENCE_HOOK
}

so clients can control better:

(1) Whether they want Attr.check to install/manage post-inference hooks on their behalf
or not. Certain clients may prefer Attr.check to not install post-inference-hooks as illustrated
by the work on <> with anonymous classes.

(2) Whether they want updates in the tree's type or not. Presently when a client wants the
tree to not be updated, the code base relies on a hack of passing a special AST fragment
called a noCheckTree.

While the original observation was to refactor Attr.check, more work will be involved in getting
rid of the noCheckTree hack: While noCheckTree discriminant is consulted only in Attr.check,
it gets passed to other methods notably Attr.checkId and gets tunnelled into Attr.check via a
host of methods all of which will likely have to also be refactored. Some of these methods are:
Attr.check, Attr.checkId, Attr.checkMethodIdInternal, Attr.checkSigPolyMethodId, Attr.checkMethodId,
Attr.checkIdInternal etc.

We may also have to tweak the enumeration a bit - There is no way to combine NO_TREE_UPDATE
and NO_INFERENCE_HOOK - though there is no use case for this ATM.