New API to export ldml files for projects which have "Share ws data" set

[hahn-kev]

Describe the feature
To update the SLDR we want a way to export the ldml file data. This will return a zip file, with the following structure
/{project-id}/**.ldlm where the source of each repo is /CachedSettings/WritingSystemStore/, however for each project we only want to include the writingsystems which have the "Share ws data" checkbox checked, see below on that.

Who is this feature for?
Admins

Looks like the attribute addToSldr will be true in SharedSettings/LexiconSettings.plsx on the WritingSystems element, if the attribute is missing then it's false. Based on this the setting is per project not per writing system.

[rmunn]

In liblcm the property AddWritingSystemsToSldr in the ProjectLexiconSettings class is what becomes addToSldr in the LexiconSettings.plsx file. It defaults to true if the project was created with LcmCache.CreateNewLangProj (i.e., what FieldWorks does when asked to create a new project), so we can probably expect most projects to have it enabled.

[rmunn]

Esimating this one as Large since it'll involve quite a bit of research. Actual code will likely be small, so perhaps Medium might be better. @hahn-kev - do you have an opinion?

[hahn-kev]

I think large is fine