Fixes crash when printing circuit with controlled MatrixGate

[RevanthGundala]

Description

Fixes #7243
This PR corrects the way Cirq prints a controlled 1×1 MatrixGate in ASCII/Unicode circuit diagrams and tidies up the underlying protocol behavior. Previously, attempting to draw a 1×1 controlled gate raised a TypeError. Now it will render correctly, and a unit test has been created to verify the output.

Changes:

matrix_gates.py
Early‑return NotImplemented for zero‑qubit MatrixGate, deferring to the fallback renderer.

circuit_diagram_info_protocol_test.py
Updated test_controlled_1x1_matrixgate_diagram_error to assert the exact rendered string:
0: ───C[[0.+1.j]]───

Testing:

Ran pytest cirq/protocols/circuit_diagram_info_protocol_test.py — all relevant tests pass.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.67%. Comparing base (5112418) to head (8e178a0).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7293   +/-   ##
=======================================
  Coverage   98.66%   98.67%           
=======================================
  Files        1106     1106           
  Lines       96086    96093    +7     
=======================================
+ Hits        94808    94815    +7     
  Misses       1278     1278           

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[daxfohl]

Lgtm cc @mhucka same thing as #6880

[mhucka]

Thank you for doing this. LGTM.