Add support for sycl accessors

This MR extends the sycl support:

• Adding function so that sycl::accessors can be used in the map_field function
• Changes the API of the cgh.parrallel_for to work like the API of sfg.function

integration/test_sycl_buffer.py

+from pystencils import Target, CreateKernelConfig, no_jit
+from lbmpy import create_lb_update_rule, LBMOptimisation
+from pystencilssfg import SourceFileGenerator, SfgConfiguration, SfgOutputMode
+from pystencilssfg.lang.cpp.sycl_accessor import sycl_accessor_ref
+import pystencilssfg.extensions.sycl as sycl
+from itertools import chain
+
+sfg_config = SfgConfiguration(
+    output_directory="out/test_sycl_buffer",
+    outer_namespace="gen_code",
+    impl_extension="ipp",
+    output_mode=SfgOutputMode.INLINE,
+)
+
+with SourceFileGenerator(sfg_config) as sfg:
+    sfg = sycl.SyclComposer(sfg)
+    gen_config = CreateKernelConfig(target=Target.SYCL, jit=no_jit)
+    opt = LBMOptimisation(field_layout="fzyx")
+    update = create_lb_update_rule(lbm_optimisation=opt)
+    kernel = sfg.kernels.create(update, "lbm_update", gen_config)
+
+    cgh = sfg.sycl_handler("handler")
+    rang = sfg.sycl_range(update.method.dim, "range")
+    mappings = [
+        sfg.map_field(field, sycl_accessor_ref(field))
+        for field in chain(update.free_fields, update.bound_fields)
+    ]
+
+    sfg.function("lb_update")(
+        cgh.parallel_for(rang)(
+            *mappings,
+            sfg.call(kernel),
+        ),
+    )