S390x test fixes (#27404)
### Description
This PR contains fixes to various big endian support issues in
onnxruntime, both in libraries and tests.
### Motivation and Context
Currently some tests from onnxruntime testsuite fail.
This change fixes all tests from onnxruntime testsuite when it's built
without training support.
It also includes a linking issue fix.
Following tests are fixed on s390x:
OrtModelOnlyTests.ValidateOrtFormatModelDoesNotRunOptimizersInFullBuild
FlatbufferUtilsTest.ExternalWriteReadWithLoadInitializers
SparseTensorConversionTests.SparseTensorProtoToDense_Rank1Indices64
SparseTensorConversionTests.SparseTensorProtoToDense_Rank1Indices32
SparseTensorConversionTests.SparseTensorProtoToDense_Rank1Indices16
SparseTensorConversionTests.SparseTensorProtoToDense_Rank1Indices8
SparseTensorConversionTests.SparseTensorProtoToDense_Rank2Indices_COO
SparseTensorConversionTests.TestConstantNodeConversion
OrtModelOnlyTests.SparseInitializerHandling
SparseTensorConversionTests.TestConstantNodeConversion
SparseTensorConversionTests.TestDenseToSparseConversion
ExecutionFrameTestInit.SparseInitializerAsOutput
CApiTest.SparseOutputModel
