Drop support for CIM14

[So-Fras]

Describe the current behavior

Powsybl currently supports the CIM14, CIM16 and CIM100 versions of the CIM.

Describe the expected behavior

Powsybl only supports CIM16 and CIM100 versions of the CIM.

Describe the motivation

The CIM14 version does not seem to be used by anyone.
Dropping the support for this version would clean the code and lighten the workload for future developments.

Extra Information

No response