(wip) fixes #1747 - provide more helpful error message running term with bad type

[samgqroberts]

aiming to fix unisonweb#1747

[samgqroberts]

At this point, given scratch file contents:

main = '(printLine "printed main")

main' = 'printLine "printed main'"

ucm will give this output when trying to run stuff:

.> run main

  😶
  
  I found this function:
  
    main : '{base.io.IO} ()
  
  but in order for me to `run` it it needs to have the type:
  
    main : '{base.io.IO} a

.> run main'

  😶
  
  I found this function:
  
    main' : base.Text ->{base.io.IO} ()
  
  but in order for me to `run` it it needs to have the type:
  
    main' : '{base.io.IO} a

.> run notfound
NameOnly notfound

  😶
  
  I looked for a function `notfound` in the most recently typechecked file and codebase but
  couldn't find one. It has to have the type:
  
    notfound : '{base.io.IO} a

Before this PR, running main' would have given the same output as running notfound.

Note that running main should successfully run the program, but I believe I'm running into unisonweb#1800

Otherwise the big TODO is to bring this new helpful error message to the situation where the term to run is found in the codebase (TODO annotated in the code) Done

[samgqroberts]

And with an empty scratch file, and main and main' added to the codebase, we get a similar helpful error message (and a similar bug from unisonweb#1800!)

.> view main

  main : '{IO} ()
  main = '(printLine "printed main")

.> view main'

  main' : Text ->{IO} ()
  main' = 'printLine "printed main'"

.> run main
NameOnly main
Just (∀ (User "()". (User "g". Var User "()" -> ({[Var User "g",#fgaev]} #568rs))))

  😶
  
  I found this function:
  
    main : '{base.io.IO} ()
  
  but in order for me to `run` it it needs to have the type:
  
    main : '{base.io.IO} a

.> run main'
NameOnly main'
Just (##Text -> (({[#fgaev]} #568rs)))

  😶
  
  I found this function:
  
    main' : base.Text ->{base.io.IO} ()
  
  but in order for me to `run` it it needs to have the type:
  
    main' : '{base.io.IO} a

.>