feat: Add break <line-number> command

[smanilov]

This makes it much easier to find the correct place to add a break point while debugging a program.

For example, now one can do the following:

$ cd test_programs/execution_success/merkle_insert/
$ nargo debug
[merkle_insert] Starting debugger
At opcode 0: BRILLIG CALL func 0: PREDICATE = %EXPR [ 1 ]%
inputs: [Single(Expression { mul_terms: [], linear_combina [...]
> next
At opcode 0.17: Const { destination: MemoryAddress(21), bi [...]
At [...]/test_programs/execution_success/merkle_insert/src/main.nr:12:3
  7    ...
  8        new_root: pub Field,
  9        leaf: Field,
 10        index: Field,
 11        mimc_input: [Field; 4]
 12 -> ) {
 13        assert(old_root == std::merkle::compute_merkle_ [...]
 14
 15        let calculated_root = std::merkle::compute_merk [...]
 16        assert(new_root == calculated_root);
 17
 18        let h = mimc::mimc_bn254(mimc_input);
 19        // Regression test for PR #891
 20        std::println(h);
 21        assert(h == 18226366069841799622585958305961373 [...]
 22    }
> break 18     # ** <- this is the new command **
Added breakpoint at opcode 0.1274
> continue
(Continuing execution...)
Stopped at breakpoint in opcode 0.1274
At opcode 0.1274: Const { destination: MemoryAddress(36),  [...]
At /home/stan/code/repos/noir/test_programs/execution_succ [...]
 13    ...
 14
 15        let calculated_root = std::merkle::compute_merk [...]
 16        assert(new_root == calculated_root);
 17
 18 ->     let h = mimc::mimc_bn254(mimc_input);
 19        // Regression test for PR #891
 20        std::println(h);
 21        assert(h == 18226366069841799622585958305961373 [...]
 22    }
>

Description

This PR is in the spirit of "submit your feature request as a PR".

Problem*

At the moment, one can only do break <opcode> and not break <line-number> in nargo debug.

Summary*

This PR adds the necessary functionality and implements the break <line-number> command.

Additional Context

I am exploring the current capabilities of nargo debug and found it would be very useful to add this command.

Documentation*

The new command automatically appears in the help command of nargo debug.

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[github-actions]

Thank you for your contribution to the Noir language.

Please do not force push to this branch after the Noir team have started review of this PR. Doing so will only delay us merging your PR as we will need to start the review process from scratch.

Thanks for your understanding.