Support `tractor.pause_from_sync()` in `brokerd`s

By passing down the `tractor.hilevel.ServiceMngr.debug_mode: bool`
(normally proxied in from the `--pdb` CLI flag) to `spawn_brokerd()` and
adjusting the `_setup_persistent_brokerd()` endpoint to do the
`tractor.devx._debug.maybe_init_greenback()` if needed.

Also in the `broker_init()` factory merge all `tractor` related `kwargs`
(i.e. `start_actor_kwargs | datad_kwargs | spawn_kws`) into the 2nd
element returned as to be passed to `ActorNursery.start_actor()`. Start
re-naming some internal vars/fields as `datad` as well.

piker/brokers/_daemon.py

@@ -61,12 +61,13 @@ async def _setup_persistent_brokerd(
     ctx: tractor.Context,
     brokername: str,
     loglevel: str | None = None,
+    debug_mode: bool = False,
 
 ) -> None:
     '''
-    Allocate a actor-wide service nursery in ``brokerd``
-    such that feeds can be run in the background persistently by
-    the broker backend as needed.
+    Allocate a actor-wide service nursery in `brokerd` such that
+    feeds can be run in the background persistently by the broker
+    backend as needed.
 
     '''
     # NOTE: we only need to setup logging once (and only) here
@@ -87,6 +88,18 @@ async def _setup_persistent_brokerd(
     from piker.data import feed
     assert not feed._bus
 
+    if (
+        debug_mode
+        and
+        tractor.current_actor().is_infected_aio()
+    ):
+        # NOTE, whenever running `asyncio` in provider's actor
+        # runtime be sure we enabled `breakpoint()` support
+        # for non-`trio.Task` usage.
+        from tractor.devx._debug import maybe_init_greenback
+        await maybe_init_greenback()
+        # breakpoint()  # XXX, SHOULD WORK from `trio.Task`!
+
     # allocate a nursery to the bus for spawning background
     # tasks to service client IPC requests, normally
     # `tractor.Context` connections to explicitly required
@@ -146,18 +159,21 @@ def broker_init(
       above.
 
     '''
-    from ..brokers import get_brokermod
-    brokermod = get_brokermod(brokername)
+    brokermod: ModuleType = get_brokermod(brokername)
     modpath: str = brokermod.__name__
-
-    start_actor_kwargs['name'] = f'brokerd.{brokername}'
-    start_actor_kwargs.update(
-        getattr(
-            brokermod,
-            '_spawn_kwargs',
-            {},
-        )
+    spawn_kws: dict = getattr(
+        brokermod,
+        '_spawn_kwargs',
+        {},
     )
+    # ^^ NOTE, here we pull any runtime parameters specific
+    # to spawning the sub-actor for the backend. For ex.
+    # both `ib` and `deribit` rely on,
+    #  `'infect_asyncio': True,` since they both
+    #  use `tractor`'s "infected `asyncio` mode"
+    #  for their libs but you could also do something like
+    #  `'debug_mode: True` which would be like passing
+    #  `--pdb` for just that provider backend.
 
     # XXX TODO: make this not so hacky/monkeypatched..
     # -> we need a sane way to configure the logging level for all
@@ -167,8 +183,7 @@ def broker_init(
 
     # lookup actor-enabled modules declared by the backend offering the
     # `brokerd` endpoint(s).
-    enabled: list[str]
-    enabled = start_actor_kwargs['enable_modules'] = [
+    enabled: list[str] = [
         __name__,  # so that eps from THIS mod can be invoked
         modpath,
     ]
@@ -180,9 +195,13 @@ def broker_init(
         subpath: str = f'{modpath}.{submodname}'
         enabled.append(subpath)
 
+    datad_kwargs: dict = {
+        'name': f'brokerd.{brokername}',
+        'enable_modules': enabled,
+    }
     return (
         brokermod,
-        start_actor_kwargs,  # to `ActorNursery.start_actor()`
+        start_actor_kwargs | datad_kwargs | spawn_kws,  # to `ActorNursery.start_actor()`
 
         # XXX see impl above; contains all (actor global)
         # setup/teardown expected in all `brokerd` actor instances.
@@ -215,10 +234,6 @@ async def spawn_brokerd(
         **tractor_kwargs,
     )
 
-    brokermod = get_brokermod(brokername)
-    extra_tractor_kwargs = getattr(brokermod, '_spawn_kwargs', {})
-    tractor_kwargs.update(extra_tractor_kwargs)
-
     # ask `pikerd` to spawn a new sub-actor and manage it under its
     # actor nursery
     from piker.service import (
@@ -236,8 +251,12 @@ async def spawn_brokerd(
             # passed to daemon_fixture_ep(**kwargs)
             brokername=brokername,
             loglevel=loglevel,
+            debug_mode=mngr.debug_mode,
         ),
         debug_mode=mngr.debug_mode,
+        # ^TODO, allow overriding this per-daemon from client side?
+        # |_ it's already supported in `tractor` so..
+
         loglevel=loglevel,
         enable_modules=(
             _data_mods