Remove unused functions from BoldIsoDateTime. Add unittests

[bero]

Summary

Removed unused functions AsISODate and AsISOTime from BoldIsoDateTime.pas and added comprehensive unit tests for all remaining functions.

Changes

Removed (dead code)

• AsISODate(d: TDate): string - not used anywhere in Bold or Attracs codebase
• AsISOTime(t: TTime): string - not used anywhere in Bold or Attracs codebase
• Controls unit dependency - was only needed for TDate type

Added

• 14 unit tests covering all Parse and As functions
• Tests for both valid inputs and error cases (invalid format, month, day, hour, minute, second)

Functions Retained (verified in use)

Function	Usage
ParseISODate	BoldVersionInfo.pas
ParseISOTime	BoldVersionInfo.pas
ParseISODateTime	BoldIDGeneratorAbstractTCPClientUnit.pas
AsISODateTime	BoldIDGeneratorAbstractTCPClientUnit.pas
AsISODateTimeMS	BoldThreadSafeLog, BoldPMappers, AttracsLogClient
AsISOTimeMS	BoldThreadSafeLog