classes: Update classes to match new bitbake class scope functionality

Move classes to classes-global or classes-recipe as appropriate to take
advantage of new bitbake functionality to check class scope/usage.

(From OE-Core rev: f5c128008365e141082c129417eb72d2751e8045)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes-recipe/image-container.bbclass

@@ -0,0 +1,27 @@
+#
+# Copyright OpenEmbedded Contributors
+#
+# SPDX-License-Identifier: MIT
+#
+
+ROOTFS_BOOTSTRAP_INSTALL = ""
+IMAGE_TYPES_MASKED += "container"
+IMAGE_TYPEDEP:container = "tar.bz2"
+
+python __anonymous() {
+    if "container" in d.getVar("IMAGE_FSTYPES") and \
+       d.getVar("IMAGE_CONTAINER_NO_DUMMY") != "1" and \
+       "linux-dummy" not in d.getVar("PREFERRED_PROVIDER_virtual/kernel"):
+        msg = '"container" is in IMAGE_FSTYPES, but ' \
+              'PREFERRED_PROVIDER_virtual/kernel is not "linux-dummy". ' \
+              'Unless a particular kernel is needed, using linux-dummy will ' \
+              'prevent a kernel from being built, which can reduce ' \
+              'build times. If you don\'t want to use "linux-dummy", set ' \
+              '"IMAGE_CONTAINER_NO_DUMMY" to "1".'
+
+        # Raising skip recipe was Paul's clever idea. It causes the error to
+        # only be shown for the recipes actually requested to build, rather
+        # than bb.fatal which would appear for all recipes inheriting the
+        # class.
+        raise bb.parse.SkipRecipe(msg)
+}