Add Share Rule

Adds an address, domain, conversation, folder or message rule. With isExclusion false it shares what it matches; with isExclusion true it hides what it matches from everyone but the owner, in both sharing modes (exclusions win). Addresses and domains are lowercased; a folder rule must name a folder on this mailbox; a message rule must name a message in it. Adding a rule that already exists returns the existing rule, and adding the same kind and value with the other flag flips it. The connection must receive emails; it need not already be sharing selected emails.