Separated AemWriter and AttitudeWriter.

src/main/java/org/orekit/files/ccsds/ndm/WriterBuilder.java

.../java/org/orekit/files/ccsds/ndm/adm/aem/AemMetadata.java

...in/java/org/orekit/files/ccsds/ndm/adm/aem/AemWriter.java

...va/org/orekit/files/ccsds/ndm/adm/aem/AttitudeWriter.java

...rg/orekit/files/ccsds/ndm/adm/aem/StreamingAemWriter.java

...in/java/org/orekit/files/ccsds/ndm/adm/apm/ApmWriter.java

...in/java/org/orekit/files/ccsds/ndm/odm/ocm/OcmWriter.java

...in/java/org/orekit/files/ccsds/ndm/odm/oem/OemWriter.java

...in/java/org/orekit/files/ccsds/ndm/odm/omm/OmmWriter.java

...in/java/org/orekit/files/ccsds/ndm/odm/opm/OpmWriter.java

src/main/java/org/orekit/files/ccsds/ndm/tdm/TdmWriter.java

...org/orekit/files/ccsds/utils/generation/KvnGenerator.java

...rg/orekit/files/ccsds/ndm/adm/aem/AttitudeWriterTest.java

...rekit/files/ccsds/ndm/adm/aem/StreamingAemWriterTest.java

...ava/org/orekit/files/ccsds/ndm/adm/apm/APMParserTest.java

...ava/org/orekit/files/ccsds/ndm/odm/ocm/OcmParserTest.java

...rekit/files/ccsds/ndm/odm/oem/StreamingOemWriterTest.java

...ava/org/orekit/files/ccsds/ndm/odm/omm/OmmParserTest.java

...ava/org/orekit/files/ccsds/ndm/odm/opm/OpmParserTest.java

...st/java/org/orekit/files/ccsds/ndm/tdm/TdmParserTest.java