[SYCL] Fix kernel name mangling for CUDA/HIP with Microsoft ABI host

SYCL kernel names are generated during template instantiation using
MangleContext, which produces different encodings based on target ABI.
When host compilation uses Microsoft ABI and device compilation targets
Itanium ABI (CUDA/HIP), this caused runtime kernel lookup failures:

  No kernel named _ZTSZZ21performIncrementationENK... was found

The issue occurred because Sema::PerformPendingInstantiations() used
ASTContext::createMangleContext(), which creates an ABI-specific context
for the primary target. In cross-ABI scenarios (Microsoft host + Itanium
device), this produced inconsistent names between host and device.

Solution:
- Added createSYCLMangleContext() helper that detects Microsoft-to-Itanium
  ABI scenarios
- When detected, uses createDeviceMangleContext() for host compilation to
  ensure Itanium mangling on both sides
- Applied to both host and device compilation phases via
  (LangOpts.SYCLIsHost || LangOpts.SYCLIsDevice) guard

This ensures identical kernel names across compilations, allowing runtime
lookup to succeed.

Fixes CMPLRLLVM-69642

Author: kekaczma