Fix for issue open62541/open62541#6205: Different data types for namespace indexes used.

[sebschwinn]

Fix for issue #6205 Different data types for namespace indexes used.
Changed prototypes and functions for namespace methods from size_t to UA_UInt16. Also updated the affected tests.

[CLAassistant]

All committers have signed the CLA.

[sebschwinn]

Hello all,
Unfortunately I am not able to evaluate the error of the CI-processes of msys64 (and clang) on my own. Can anybody support me? Or has anybody else seen a fix for this? The command includes the -NonInteractive flag, but the process still wants to read credentials, which is (as of my knowledge) not possible.
Greetings,
Sebastian

[jpfr]

Thanks we'll look into it.

[mcpat]

Is there a reason why you do not change the prototypes and implementations of the internal functions getNamespaceByIndex and getNamespaceByName? It would be great if the public and internal prototypes remain identical.