Move function contents from napi5 to NexusFile (#39484)

### Description of work

The following have been identified as simple enough that they can be
directly copied into corresponding NexusFile method with minimal further
refactoring
- NX5makegroup() --> File::makeGroup()
- NX5opengroup() --> File::openGroup()
- NX5closegroup() --> File::closeGroup()
- NX5compmakedata64() --> File::makeCompData()
- NX5opendata() --> File::openData()
- NX5putdata() --> File::putData(NumT const *data)  (there are many,
here signature matters)
- NX5closedata() --> File::closeData()
- NX5putslab64() --> File::putSlab(NumT const *data, DimSizeVector const
&start, DimSizeVector const &size) (this signature)
- NX5getslab64() --> File::getSlab()
- NX5makelink() --> File::makeLink()
- NX5getdataID() --> File::getDataID()
- NX5getgroupID() --> File::getGroupID()
- NX5flush() --> File::flush()



Relates to [EWM
11786](https://ornlrse.clm.ibmcloud.com/ccm/web/projects/Neutron%20Data%20Project%20%28Change%20Management%29#action=com.ibm.team.workitem.viewWorkItem&id=11786)

### To test:

This is moving functionality from `napi5.cpp` to `NexusFile.cpp` so all
existing tests should pass.

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Author: searscr

Framework/Nexus/CMakeLists.txt

@@ -25,10 +25,10 @@ set(TEST_FILES
     NexusIOHelperTest.h
     NexusClassesTest.h
     NexusDescriptorTest.h
-    NeXusFileTest.h
-    NeXusFileLeakTest.h
-    NeXusFileNapiTest.h
-    NeXusFileReadWriteTest.h
+    NexusFileTest.h
+    NexusFileLeakTest.h
+    NexusFileNapiTest.h
+    NexusFileReadWriteTest.h
     NapiUnitTest.h
 )
 

Framework/Nexus/inc/MantidNexus/NexusFile.h

@@ -646,7 +646,7 @@ class MANTID_NEXUS_DLL File {
    *
    * \param link The object (group or data) in the file to link to.
    */
-  void makeLink(NXlink &link);
+  void makeLink(NXlink const &link);
 };
 
 /**