Refactor use of name, tmp, show triplet

[abelsiqueira]

There are $2^3 = 8$ possibilities. Refactor so these are clear.
Possibly create a function to assist.

A possible implementation is using Val. E.g.,

function foo(::Val{true}, x)
  return x + 1
end

function foo(::Val{false}, x)
  return x - 1
end

function foo(x)
  if x > 0
    return foo(Val(true), x)
  else
    return foo(Val(false), x)
  end
end

[suvayu]

Some notes on behaviour, for a given source:

1. source is a file:
   return show ? DataFrame(...) | table_name

   name	tmp	remarks
   non-empty	as provided
   empty	true	table name: t_<safe_filename>
   empty	false	table name: <safe_filename>

   The above behaviour reduces the coupled possibilities to only 2. When name is empty, the generated table name differs based on tmp.

2. source is another table: TBD since now the scope of TIO also
   includes use as a library by TEM.