Make circuit rendering of PhasedISwapPowGate consistent with other gates

[viathor]

Before:

In [3]: cirq.Circuit([cirq.PhasedXPowGate(phase_exponent=0.1, exponent=0.2).on(q0), cirq.ISWAP(q0, q1)**0.3, cirq.PhasedISwapPowGate(phase_exponent=0.4, exponent=0.5).on(q0, q1)])

Out[3]: 
0: ───PhX(0.1)^0.2───iSwap───────PhasedISWAP**0.5───
                     │           │
1: ──────────────────iSwap^0.3───#2─────────────────

After:

In [3]: cirq.Circuit([cirq.PhasedXPowGate(phase_exponent=0.1, exponent=0.2).on(q0), cirq.ISWAP(q0, q1)**0.3, cirq.PhasedISwapPowGate(phase_exponent=0.4, exponent=0.5).on(q0, q1)])

Out[3]: 
0: ───PhX(0.1)^0.2───iSwap───────PhISwap(0.4)───────
                     │           │
1: ──────────────────iSwap^0.3───PhISwap(0.4)^0.5───