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

tests/generator_scripts/scripts/TestSyclBuffer.py

+import pystencils as ps
+import sympy as sp
+from pystencilssfg import SourceFileGenerator
+from pystencilssfg.lang.cpp.sycl_accessor import sycl_accessor_ref
+import pystencilssfg.extensions.sycl as sycl
+
+
+with SourceFileGenerator() as sfg:
+    sfg = sycl.SyclComposer(sfg)
+
+    u_src, u_dst, f = ps.fields("u_src, u_dst, f : double[2D]", layout="fzyx")
+    h = sp.Symbol("h")
+
+    jacobi_update = [
+        ps.Assignment(
+            u_dst.center(),
+            (h**2 * f[0, 0] + u_src[1, 0] + u_src[-1, 0] + u_src[0, 1] + u_src[0, -1])
+            / 4,
+        )
+    ]
+
+    kernel_config = ps.CreateKernelConfig(target=ps.Target.SYCL)
+    jacobi_kernel = sfg.kernels.create(jacobi_update, config=kernel_config)
+
+    cgh = sfg.sycl_handler("handler")
+    rang = sfg.sycl_range(2, "range")
+    mappings = [
+        sfg.map_field(u_src, sycl_accessor_ref(u_src)),
+        sfg.map_field(u_dst, sycl_accessor_ref(u_dst)),
+        sfg.map_field(f, sycl_accessor_ref(f)),
+    ]
+
+    sfg.function("jacobiUpdate")(
+        cgh.parallel_for(rang)(*mappings, sfg.call(jacobi_kernel)),
+    )