Inconsistent room creation behavior for history visibility

[gabrc52]

When creating private rooms outside of a space, Element Web, Element Android and Element iOS set history visibility to shared.

When creating non-public rooms inside a space, Element Android an Element iOS set history visibility to shared, however Element Web sets it to invite.

In my opinion, Element Android and Element iOS have the best behavior, since I believe if someone creates a room in a space and makes it visible from space members, and the space is already public, the most sensible option is to share all the history, like most rooms on matrix.org.

[richvdh]

This is closely related to matrix-org/matrix-spec#633, which notes that there is no clear definition of "private room".

Seems to be a duplicate of #377