profile/systemd-osc-context: Remove invalid octets

UAPI.15 requires:
* No C0 Control Characters (`\x00-\x1f`)
* No DEL character (`\x7f`)

The following would be nice, but requires a `sed` implementation that is
aware of UTF-8: `-e $'y/\x00-\x1f\x7f/␀-␟␡/'`.

References:
 [0] https://uapi-group.org/specifications/specs/osc_context/#general-syntax

profile.d/80-systemd-osc-context.sh

@@ -28,7 +28,7 @@ __systemd_osc_context_escape() {
     # uuids, id128, hostnames, usernames, since they all come with syntax
     # requirements that exclude \ and ; anyway. This hence primarily is about
     # escaping the current working directory.
-    echo "$1" | sed -e 's/\\/\\x5c/g' -e 's/;/\\x3b/g'
+    echo "$1" | sed -e 's/\\/\\x5c/g' -e 's/;/\\x3b/g' -e 's/[[:cntrl:]]/⍰/g'
 }
 
 __systemd_osc_context_common() {