XWIKI-8820: Introduce framework to stream wiki data from one representation to another

pom.xml

xwiki-platform-wikistream-api/pom.xml

...ikistream/descriptor/DefaultWikiStreamBeanDescriptor.java

.../descriptor/DefaultWikiStreamBeanParameterDescriptor.java

...xwiki/wikistream/descriptor/WikiStreamBeanDescriptor.java

...org/xwiki/wikistream/descriptor/WikiStreamDescriptor.java

...i/wikistream/descriptor/WikiStreamPropertyDescriptor.java

.../main/java/org/xwiki/wikistream/filter/UnknownFilter.java

...va/org/xwiki/wikistream/input/InputWikiStreamFactory.java

...va/org/xwiki/wikistream/input/source/FileInputSource.java

...n/java/org/xwiki/wikistream/input/source/InputSource.java

...xwiki/wikistream/input/source/InputStreamInputSource.java

.../org/xwiki/wikistream/input/source/ReaderInputSource.java

...ki/wikistream/internal/AbstractBeanWikiStreamFactory.java

.../java/org/xwiki/wikistream/internal/filter/AllFilter.java

...am/internal/input/AbstractBeanInputWikiStreamFactory.java

...istream/internal/input/source/DefaultFileInputSource.java

.../internal/input/source/DefaultInputStreamInputSource.java

...tream/internal/input/source/DefaultReaderInputSource.java

...i/wikistream/internal/input/source/StringInputSource.java