Simplify add and remove verbatim box

[sesmart]

Describe the feature you'd like

Creating a verbatim box needs target_circuit = Circuit().add_verbatim_box(target_circuit), which is the only instruction with this pattern. There is also is no way to easily remove a verbatim box from a circuit, besides creating a new circuit. This is questionable for partial verbatim boxes as well.

How would this feature be used? Please describe.

1. Custom or piece-wise compilation
2. Running verbatim on particular simulators (i.e. with noise models)
3. Modifying nativized or previously modified circuits
4. Simplifying creating verbatim circuits

There are a few options:

1. Add self as an argument target_circuit.add_verbatim_box(), since it is always implied that we have access to the targeted instructions of interest
2. Simplify the call, potentially to a ; target_circuit.verbatim() with a flag for removal, or even to target particular ranges of instruction
3. Add a remove verbatim method, or add a remove flag to a .verbatim method could either (1) remove all verbatim boxes, or (2) remove the k-th box.

Describe alternatives you've considered
Current behavior for a single verbatim:

new = Circuit()
for ins in target_circuit.instructions:
    if "verbatim" not in ins.name.lower():
         new.add_instruction(ins)

or

from braket.circuis.compiler_directives import StartVerbatimBox, EndVerbatimBox
new = Circuit()
for ins in target_circuit.instructions:
    if not isinstance(ins, (StartVerbatimBox, EndVerbatimBox)):
        new.add_instruction(ins)

This is okay for removing all boxes, but it is slightly more complicated if you want to remove only a single box.

Additional context
Should require no changes to the existing serialization.