Switch to strict-eg nurseries almost everywhere

That is just throughout the core library, not the tests yet. Again, we
simply change over to using our (nearly equivalent?)
`.trionics.collapse_eg()` in place of the already deprecated
`strict_exception_groups=False` flag in the following internals,
- the conc-fan-out tn use in `._discovery.find_actor()`.
- `._portal.open_portal()`'s internal tn used to spawn a bg rpc-msg-loop
  task.
- the daemon and "run-in-actor" layered tn pair allocated in
  `._supervise._open_and_supervise_one_cancels_all_nursery()`.

The remaining loose-eg usage in `._root` and `._runtime` seem to be
necessary to keep the test suite green?? For the moment these are left
out.

tractor/_discovery.py

@@ -28,7 +28,10 @@ from typing import (
 from contextlib import asynccontextmanager as acm
 
 from tractor.log import get_logger
-from .trionics import gather_contexts
+from .trionics import (
+    gather_contexts,
+    collapse_eg,
+)
 from .ipc import _connect_chan, Channel
 from ._addr import (
     UnwrappedAddress,
@@ -88,7 +91,6 @@ async def get_registry(
             yield regstr_ptl
 
 
-
 @acm
 async def get_root(
     **kwargs,
@@ -249,9 +251,12 @@ async def find_actor(
         for addr in registry_addrs
     )
     portals: list[Portal]
-    async with gather_contexts(
+    async with (
+        collapse_eg(),
+        gather_contexts(
             mngrs=maybe_portals,
-    ) as portals:
+        ) as portals,
+    ):
         # log.runtime(
         #     'Gathered portals:\n'
         #     f'{portals}'

tractor/_portal.py

@@ -39,7 +39,10 @@ import warnings
 
 import trio
 
-from .trionics import maybe_open_nursery
+from .trionics import (
+    maybe_open_nursery,
+    collapse_eg,
+)
 from ._state import (
     current_actor,
 )
@@ -558,14 +561,13 @@ async def open_portal(
     assert actor
     was_connected: bool = False
 
-    async with maybe_open_nursery(
+    async with (
+        collapse_eg(),
+        maybe_open_nursery(
             tn,
             shield=shield,
-        strict_exception_groups=False,
+        ) as tn,
-        # ^XXX^ TODO? soo roll our own then ??
+    ):
-        # -> since we kinda want the "if only one `.exception` then
-        # just raise that" interface?
-    ) as tn:
 
         if not channel.connected():
             await channel.connect()

tractor/_rpc.py

@@ -756,7 +756,6 @@ async def _invoke(
             BaseExceptionGroup,
             BaseException,
             trio.Cancelled,
-
         ) as _scope_err:
             scope_err = _scope_err
             if (

tractor/_supervise.py

@@ -42,6 +42,7 @@ from ._runtime import Actor
 from ._portal import Portal
 from .trionics import (
     is_multi_cancelled,
+    collapse_eg,
 )
 from ._exceptions import (
     ContextCancelled,
@@ -324,9 +325,10 @@ class ActorNursery:
         server: IPCServer = self._actor.ipc_server
 
         with trio.move_on_after(3) as cs:
-            async with trio.open_nursery(
+            async with (
-                strict_exception_groups=False,
+                collapse_eg(),
-            ) as tn:
+                trio.open_nursery() as tn,
+            ):
 
                 subactor: Actor
                 proc: trio.Process
@@ -419,10 +421,10 @@ async def _open_and_supervise_one_cancels_all_nursery(
     # `ActorNursery.start_actor()`).
 
     # errors from this daemon actor nursery bubble up to caller
-    async with trio.open_nursery(
+    async with (
-        strict_exception_groups=False,
+        collapse_eg(),
-        # ^XXX^ TODO? instead unpack any RAE as per "loose" style?
+        trio.open_nursery() as da_nursery,
-    ) as da_nursery:
+    ):
         try:
             # This is the inner level "run in actor" nursery. It is
             # awaited first since actors spawned in this way (using
@@ -432,11 +434,10 @@ async def _open_and_supervise_one_cancels_all_nursery(
             # immediately raised for handling by a supervisor strategy.
             # As such if the strategy propagates any error(s) upwards
             # the above "daemon actor" nursery will be notified.
-            async with trio.open_nursery(
+            async with (
-                strict_exception_groups=False,
+                collapse_eg(),
-                # ^XXX^ TODO? instead unpack any RAE as per "loose" style?
+                trio.open_nursery() as ria_nursery,
-            ) as ria_nursery:
+            ):
-
                 an = ActorNursery(
                     actor,
                     ria_nursery,