Add Family member to Ancestor Tree

[jittymolmathew92]

The UI implementation for add new family member against a person is included in this PR.

There is no backend integration.

[DavidMStraub]

Some UX considerations:

• the view needs an "edit mode" (with pencil FAB, blue app bar etc., like the object views) - plus signs should only displayed in tedit mode
• We should not offer "father" and "mother" as options to people who already have father and mother. While people can have multiple parent families (when adopted etc.), this is not something that is unique enough to handle from a tree view.

Next, you can implement the backend logic. But this is too complicated to implement from scratch: it can all be done via firing edit:action events. The problem is that these events are currently handled in GrampjsViewObject, from which GrampsjsViewTreeChartBase does not inherit. So it's best to move this handling logic somewhere up in the stack (perhaps even GrampsJs.js) or into a mixing. I suggest to feed this comment as prompt to Claude and ask it to do a tradeoff analysis of possible architectures and recommend one.