Relax character filtering

By default, the character filtering service filters out ranges of characters, which include e.g. charaters used for emojis (see https://github.com/nuxeo/nuxeo/blob/160182725c610a9b18190f7f997c490c55ec5d47/nuxeo-core/nuxeo-core/src/main/java/org/nuxeo/ecm/core/filter/CharacterFilteringServiceImpl.java#L61). These filters cannot be disabled as they are part of the service code.

Make it easier to override these mandatory filters.

Side note: the Nuxeo Platform allows the use of emoji unicode in the document name.