Add bash completion provided by upstream

debian/clevis.bash-completion

@@ -0,0 +1,2 @@
+
+usr/share/bash-completion/completions/clevis

debian/control

@@ -6,6 +6,7 @@ Vcs-Browser: https://git.in-ulm.de/cbiedl/clevis
 Vcs-Git: https://git.in-ulm.de/cbiedl/clevis.git
 Build-Depends: debhelper (>= 11~),
     asciidoctor,
+    bash-completion,
     curl,
     dracut (>= 047+31-1~),
     jose,

debian/not-installed

@@ -0,0 +1,5 @@
+
+# Appearently it's necessary to list the bash completion here
+# else dh_missing will complain. Don't worry, the completion file
+# still gets installed.
+usr/share/bash-completion/completions/clevis

debian/rules

@@ -5,7 +5,7 @@ DPKG_EXPORT_BUILDFLAGS = 1
 include /usr/share/dpkg/buildflags.mk
 
 %:
-	dh $@
+	dh $@  --with=bash-completion
 
 override_dh_missing:
 	dh_missing --fail-missing