bitbake: bitbake: Add copyright headers where missing

Where copyright headers were not present, add them to make things
clear.

(Bitbake rev: e591325b2bd901c381003deb96a7b32a7148e93e)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 1aa338a216350a2751fff52f866039343e9ac013)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake-prserv

@@ -1,5 +1,7 @@
 #!/usr/bin/env python3
 #
+# Copyright BitBake Contributors
+#
 # SPDX-License-Identifier: GPL-2.0-only
 #
 

bitbake/bin/bitbake-worker

@@ -1,5 +1,7 @@
 #!/usr/bin/env python3
 #
+# Copyright BitBake Contributors
+#
 # SPDX-License-Identifier: GPL-2.0-only
 #
 

bitbake/bin/git-make-shallow

@@ -1,5 +1,7 @@
 #!/usr/bin/env python3
 #
+# Copyright BitBake Contributors
+#
 # SPDX-License-Identifier: GPL-2.0-only
 #