[SYCL] Support build with shared libzstd (#22294)

[sarnex]

Cherry pick of 2594da5

Distros of Fedora family package only shared libzstd build against which was not fully supported. This commit addresses the gap in a similar way as it's already handled in few other cases in llvm. See for reference:

llvm/llvm/lib/Support/CMakeLists.txt

Lines 28 to 38 in b09acde

	if(LLVM_ENABLE_ZSTD)
	if(TARGET zstd::libzstd_shared AND NOT LLVM_USE_STATIC_ZSTD)
	set(zstd_target zstd::libzstd_shared)
	else()
	set(zstd_target zstd::libzstd_static)
	endif()
	endif()
	if(LLVM_ENABLE_ZSTD)
	list(APPEND imported_libs ${zstd_target})
	endif()

and:

llvm/lld/ELF/CMakeLists.txt

Lines 9 to 18 in b09acde

	if(LLVM_ENABLE_ZSTD)
	if(TARGET zstd::libzstd_shared AND NOT LLVM_USE_STATIC_ZSTD)
	set(zstd_target zstd::libzstd_shared)
	else()
	set(zstd_target zstd::libzstd_static)
	endif()
	endif()
	if(LLVM_ENABLE_ZSTD)
	list(APPEND imported_libs ${zstd_target})

Fixes: #22310

CC: @sarnex