interactive: return str(operation) instead of operation

[dshaaban01]

get_all_possible_rewrites() returns the op_idx (among other variables), which is used in compute_available_pass_list() in order to get the op to later print it. We thus run op = list(self.current_module.walk())[op_idx] twice for every operation (we already compute this for every operation in get_all_possible_rewrites() )

I tried two solutions:

1. returning the str(Operation) from get_all_possible_rewrites():

However, when the rewrite is displayed in the gui, we now get

%0 = arith.addi %1, %2 instead of
Addi(%res = arith.addi %two, %n : i32)

2. returning the Operation from get_all_possible_rewrites() - (This wont work either way due to issues with testing and equality checking of an Operation, but added it here for completeness):

When the rewrite is displayed in the gui, we now get

Addi(%0 = arith.addi %1, %2)
instead of
Addi(%res = arith.addi %two, %n : i32)

Not sure why we lose the information (i.e. the names of the user defined regs).

[superlopuh]

Fixed in #3601