Test XZ support and update LZMA for N5Store arrays

Adds some tests for XZ support in N5 using Numcodecs' LZMA compressor
with specific options. Also tests LZMA options that are not currently
supported by N5 to ensure they still warn and are handled correctly.

zarr/tests/test_core.py

@@ -1602,6 +1602,10 @@ def test_compressors(self):
         compressors = [
             None, BZ2(), LZ4(), Zlib(), GZip()
         ]
+        if LZMA:
+            compressors.append(LZMA())
+            compressors.append(LZMA(preset=1))
+            compressors.append(LZMA(preset=6))
         for compressor in compressors:
             a1 = self.create_array(shape=1000, chunks=100, compressor=compressor)
             a1[0:100] = 1
@@ -1613,7 +1617,7 @@ def test_compressors(self):
             Blosc()
         ]
         if LZMA:
-            compressors_warn.append(LZMA())
+            compressors_warn.append(LZMA(2))  # Try lzma.FORMAT_ALONE, which N5 doesn't support.
         for compressor in compressors_warn:
             with pytest.warns(RuntimeWarning):
                 a2 = self.create_array(shape=1000, chunks=100, compressor=compressor)