fix: meter widget not using limits defined in editor when pv missing display limits

[cjenkscybercom]

To replicate the issue / test first run:

softIocPVA -d CSSTUDIO-1339.db

Then, open CSSTUDIO-1339.bob in CSStudio

Archive.zip

[shroffk]

Looks like a reasonable check

[kasemir]

Looks good.
Kunal, note that there's still the related VType range issue epics-base/epicsCoreJava#56:
We can't have just a minimum display limit without a maximu,, or just a HIGH warning without a LOW.
On the record, you can set just HIGH, and LOW is then reported as NaN. But the VType wants to create a LOW..HIGH Range where both ends are valid.