Fix BitShift UB when shift amount >= bit width

[Copilot]

Description

Shifting by >= the bit width of an unsigned type is undefined behavior in C++. On x86-64, the hardware masks 64-bit shift amounts to 6 bits, so x >> 64 silently becomes x >> 0, returning the original value instead of 0.

Added SafeShiftLeft/SafeShiftRight helpers that return 0 when shift >= sizeof(T) * 8, applied across all three broadcast code paths (scalar-X, scalar-Y, element-wise).

template <typename T>
inline T SafeShiftRight(T value, T shift) {
  return shift >= sizeof(T) * 8 ? T{0} : value >> shift;
}

Added tests covering:

• Shift by exact bit width (32, 64) for uint32_t and uint64_t
• Shift by more than bit width (65, 128)
• All three broadcast paths (scalar-X, scalar-Y, element-wise)
• New tests are excluded for DirectML EP, which has the same hardware-level shift masking behavior

Motivation and Context

BitShift with direction="RIGHT" on uint64 inputs with shift amount 64 returns the original values instead of zeros. Reproduces with CPUExecutionProvider and ORT_DISABLE_ALL (constant folding masks the bug under ORT_ENABLE_ALL).

[tianleiwu]

@copilot, DirectML CI pipeline failed:
[ FAILED ] BitShiftOpTest.LeftShiftByBitWidth_Uint64
[ FAILED ] BitShiftOpTest.RightShiftByBitWidth_Uint32
[ FAILED ] BitShiftOpTest.ScalarLeftShiftByBitWidth_Uint64
Please skip those tests for DirectML EP.

[Copilot]

@copilot, DirectML CI pipeline failed:
[ FAILED ] BitShiftOpTest.LeftShiftByBitWidth_Uint64
[ FAILED ] BitShiftOpTest.RightShiftByBitWidth_Uint32
...

Excluded kDmlExecutionProvider from all six new BitShift shift-by-bit-width tests in commit 878dded.