Remove napi5 and most of napi test layer (#39691)

### Description of work

#### Summary of work

With PR #39657, now `napi5` is almost completely unused, and `napi` is
only being used for `NXopenaddress` (to be removed in PR #39658). It is
therefore safe at this point to remove `napi5` and most of the tests of
`napi`.

The following have been left in the `napi` layer:
- `napi` because `NXopenaddress` is still being called, and it is needed
for the remaining tests to work
- `NapiUnitTest` because it may have useful tests to be duplicated in
`NexusFileTest`, and contains some notes on proper functionality
- `napi_test_cpp` because it is actually a test of `Nexus::File`
- `test_nxunlimited` because it has a useful test of unlimited
dimensions that doesn't seem to be replicated in other tests

Part of #38332
EWM 11399

#### Further detail of work

Lots of deletions.  It feels good.

Note that `napi.cpp` now implements `NXgetdata` and `NXgetchardata` from
`napi5`. These methods now *only* show up in the tests of the `napi`
layer, so it doesn't particularly matter how this is implemented at this
point so long as the tests pass.

### To test:

This is a refactor. The existing tests passing, in particular tests in
the Nexus and DataHandling layers, should suffice.

This does not require release notes because it is a purely internal
matter.
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---

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Author: rboston628

Framework/DataHandling/src/LoadISISNexus2.cpp

@@ -386,6 +386,7 @@ void LoadISISNexus2::exec() {
   m_spec.clear();
   m_monitors.clear();
   m_wsInd2specNum_map.clear();
+  m_nexusFile->close();
 }
 /**
 Check for a set of synthetic logs associated with multi-period log data. Raise

Framework/Nexus/CMakeLists.txt

@@ -2,7 +2,6 @@ set(SRC_FILES
     src/H5Util.cpp
     src/NexusClasses.cpp
     src/napi.cpp
-    src/napi5.cpp
     src/napi_helper.cpp
     src/NexusDescriptor.cpp
     src/NexusException.cpp
@@ -16,7 +15,6 @@ set(INC_FILES
     inc/MantidNexus/NexusIOHelper.h
     inc/MantidNexus/NexusFile_fwd.h
     inc/MantidNexus/napi.h
-    inc/MantidNexus/napi5.h
     inc/MantidNexus/napi_helper.h
     inc/MantidNexus/NexusDescriptor.h
     inc/MantidNexus/NexusException.h

Framework/Nexus/inc/MantidNexus/NexusFile_fwd.h

@@ -82,7 +82,7 @@ typedef struct {
  * \li EOD end of file -1
  * \ingroup cpp_types
  */
-enum class NXstatus : const int { NX_OK = 1, NX_ERROR = 0, NX_EOD = -1 };
+enum class NXstatus : const int { NX_OK = 1, NX_ERROR = 0 };
 
 /*--------------------------------------------------------------------------*/
 

Framework/Nexus/inc/MantidNexus/napi5.h

@@ -6,8 +6,6 @@
 
 #include <hdf5.h>
 
-MANTID_NEXUS_DLL pNexusFile5 NXI5assert(NXhandle fid);
-
 MANTID_NEXUS_DLL herr_t readStringAttribute(hid_t attr, char **data);
 
 MANTID_NEXUS_DLL herr_t readStringAttributeN(hid_t attr, char *data, std::size_t maxlen);

Framework/Nexus/inc/MantidNexus/napi_helper.h

@@ -20,7 +20,14 @@ using std::string;
 using std::stringstream;
 using std::vector;
 
+#ifdef H5_VERSION_GE
+#if !H5_VERSION_GE(1, 8, 0)
+#error HDF5 Version must be 1.8.0 or higher
+#endif
+#endif
+
 #ifdef WIN32
+#define snprintf _snprintf
 #define strdup _strdup
 #endif
 
@@ -1355,11 +1362,10 @@ template <typename NumT> void File::readData(std::string const &dataName, std::v
 }
 
 template <typename NumT> void File::readData(std::string const &dataName, NumT &data) {
-  std::vector<NumT> dataVector;
+  std::vector<NumT> dataVector(1, 0);
   this->openData(dataName);
   this->getData(dataVector);
-  if (!dataVector.empty())
-    data = dataVector[0];
+  data = dataVector[0];
   this->closeData();
 }