Trim survey variable names

[nfsprodriver]

As survey variables are applied as they are, we get "undefined" errors, e.g. when there are accidental spaces (in the beginning or the end). In general, variable names should never contain spaces at all so we might need a field validation for this in web2/src/components)/SurveyVars.vue This affects at least version develop-c2c4344-1658241081. I don't know, if it's also present in latest official version.

[fiftin]

@nfsprodriver Thank you.