CLI: Sharepoint: Set Libraries to default (#2634)

Issue #2631: library backup set to the default rather than all data.
- verified libraries is the default call in cli
- verified other categories can still be called if they asked for explicitly.
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#### Type of change

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- [x] 🌻 Feature

#### Issue(s)

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*closes  #2631 <issue>

#### Test Plan

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- [x] 💪 Manual

src/cli/backup/sharepoint.go

@@ -335,8 +335,9 @@ func includeAllSitesWithCategories(categories []string) *selectors.SharePointBac
 }
 
 func addCategories(sel *selectors.SharePointBackup, cats []string) *selectors.SharePointBackup {
+	// Issue #2631: Libraries are the only supported feature for SharePoint at this time.
 	if len(cats) == 0 {
-		sel.Include(sel.AllData())
+		sel.Include(sel.Libraries(selectors.Any()))
 	}
 
 	for _, d := range cats {