async: remove tag_invoke calls

P2300R9 removed usage of tag_invoke.  stdexec still has it
but in order to be forward compliant with the C++26 standard
we should modernize the code and remove its usage.  This also
has the benefit of simplifying most sender/receiver implementations.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib0a1d0a82485c8d247a18daa020d0bba2249e95c
diff --git a/src/async/fdio.cpp b/src/async/fdio.cpp
index 94c79d1..df54cf0 100644
--- a/src/async/fdio.cpp
+++ b/src/async/fdio.cpp
@@ -59,7 +59,7 @@
     }
 }
 
-void fdio_completion::arm() noexcept
+void fdio_completion::start() noexcept
 {
     // Set ourselves as the awaiting Receiver
     std::unique_lock l{fdioInstance.lock};