[CALCITE-3085] Add RelBaseShuttle, implementation of RelShuttle without stack

[laurentgo]

org.apache.calcite.rel.RelShuttleImpl class has a protected stack field used to capture parent node when visiting children, but all subclasses in Calcite codebase never read the content of the stack.

The change add a new implementation of RelShuttle named RelBasicShuttle. The implementation do not use/populate a stack.

Also make the class the base class of RelShuttleImpl, along with all the sub-classes of RelShuttleImpl (since none of them requires a stack).

[julianhyde]

Has this issue shown up empirically?

The stack is implemented as an ArrayDeque, so push and pop should be very few machine instructions.

RelShuttleImpl is not the only possible implementation of RelShuttle. It is just a good general-purpose implementation. If it doesn't meet your needs, you can create your own.

No sub-classes in Calcite use the stack field, but it's there, and it is potentially useful, if I am looking for say a Filter within a Project within a Filter.

Consider AbstractList class in the JDK. It contains a modCount field is useful for most implementations (prevents concurrent modifications) but is unnecessary overhead for sub-classes that are immutable. To avoid that overhead, I created AbstractImmutableList, but I wouldn't suggest removing modCount from AbstractList.

[laurentgo]

Sorry @julianhyde I just saw the email notification from JIRA, and replied within the ticket. Following the conversation here, I will push a new commit against master (there's no point of keeping the current commit)