Publish diagnostic if an unknown unit of time is being used for a duration

[rcjsuen]

The following Dockerfile will not build but no diagnostic is being published for the invalid 1s1x duration.

FROM alpine
HEALTHCHECK --interval=1s1x CMD ls

$ docker build .
Sending build context to Docker daemon  86.15MB
Step 1/2 : FROM alpine
latest: Pulling from library/alpine
88286f41530e: Pull complete
Digest: sha256:1072e499f3f655a032e88542330cf75b02e7bdf673278f701d7ba61629ee3ebe
Status: Downloaded newer image for alpine:latest
 ---> 7328f6f8b418
Step 2/2 : HEALTHCHECK --interval=1s1x CMD ls
time: unknown unit x in duration 1s1x

[rcjsuen]

Actually, just read the error message more carefully and realized that this is a completely new diagnostic that needs to be published.