Multi-target gates are rendered unclearly in ASCII art circuits

[Morcifer]

This issue is a followup of issue #1476 and this comment in the PR that solved it.

Simple gates in the case of measurements use vertical lines to show which qubits are involved:

q_0    ── H ─────────── ● ──── M ──
                        │      ╘═══
q_1    ── H ──── X ──── X ─────────

But when rendering circuits where there is one gate that operates on multiple targets and there are no measurements, the rendering is somewhat unclear.

For example the circuit in the test custom_intrinsic_mixed_args in compiler/qsc/src/interpret/circuit_tests.rs renders as

q_0    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──
q_1    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──
q_2    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──
q_3    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──
q_4    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──
q_5    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──
q_6    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──
q_7    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──
q_8    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──
q_9    ─ AccountForEstimatesInternal([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)], 1) ──

while circuits such as:

use q0 = Qubit();
use q1 = Qubit();
Rxx(1.0, q0, q1);

use q2 = Qubit();
use q3 = Qubit();
Rxx(1.0, q2, q3);

render as

q_0    ─ rxx(1.0000) ─
q_1    ─ rxx(1.0000) ─
q_2    ─ rxx(1.0000) ─
q_3    ─ rxx(1.0000) ─

It would be nice if multi-target gates would be rendered a bit more clearly, to explicitly show which qubits are the ones that are connected.