Spawn macro does not compose with logging macros

[Octogonapus]

Dagger v0.18.9, Julia v1.10.3

julia> Dagger.@spawn begin
           @debug "x"
       end
ERROR: LoadError: syntax: invalid syntax (escape (outerref @debug))
Stacktrace:
 [1] top-level scope
   @ REPL[4]:1
in expression starting at REPL[4]:2

[jpsamaroo]

Similar to #479 and #480, @spawn currently requires a function call as the top-level expression. This is for many reasons, most prominently because it makes it easily possible to track synchronization dependencies. We can and should implement a more capable parser, but it's not entirely trivial to implement, and can lead to some surprising behavior if users aren't careful.