feat: Allow skipping child streams by returning an empty child context from parent stream

[edgarrmondragon]

Feature scope

Taps (catalog, state, stream maps, etc.)

Description

Some pseudocodish approach would be:

class ParentStream:
  # Custom tap implementation
  def get_child_context(self, record, context):
    if not record["has_children_records"]:

  # Part of the SDK
  def _sync_children(self, child_context):
    if not child_context:
      logger.warning(
        "Context for child streams of '%s' is empty, skipping sync of any child streams",
        self.name,
      )
      return
    for child_stream in self.child_streams:
      if child_stream.selected or child_stream.has_selected_descendents:
        child_stream.sync(context=child_context)