Resolved issue of compas (mag_adc[]) curves

[demvlad]

Resolved issue of empty string value at compas (mag_adc[]) curves legend:
-added friendly legends caption for fields
-added data transform for curves Min-Max values
To prevent similar issue for other unknown fields, the default friendly legends caption is changed from empty string to raw fields value.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[nerdCopter]

please screenshot before/after (or errored console if applicable)

[demvlad]

please screenshot before/after (or errored console if applicable)

@nerdCopter
Yes, of course:
Test file:
compas_test.txt

The master branch

This PR

To prevent this issue for other fields, what have not friendly values transform, the default value is changed in 2nd commit. The raw value is better than nothing.