Improve the compatibility of the input masking and data validation features

[JaneSjs]

User case: https://surveyjs.answerdesk.io/internal/ticket/details/T19433

Numeric validation doesn't work if saveMaskedValue is enabled, because we validate a saved string value. We adviced the user to call convertToNumber function for validation, but it seems that we could call it in our code instead of the user's.

survey-library/packages/survey-core/src/functionsfactory.ts

Line 153 in 2dbe2f5

function convertToNumber(val: any): number {