Linking to the 'add owner' screen

[DmitryBespalov]

As a new safe member,
I want to be added to the safe,
So that I could start using it.

As a safe owner,
I want to add new member to the owners list,
So that they could start using it.

Overview:

• Mobile app provides a way for new owners to join existing safe. In short, it works like this:
  • To-be-added owner shares a link with the safe owner
  • Safe owner opens link and adds a new owner or replaces existing owner with the address from the link
• Those links used to be supported before rewrite of the web ui
• This functionality is used by ~10% of mobile users

URI pattern:

 {web app}/{chain prefix}:{safe address}/addOwner?address={new owner address}

Example of a link

https://app.safe.global/gor:0xabcdEEeEeEeEeEeEeEeEabCdEeeEEEEEEEeeEEeE/addOwner?address=0xaABCdeeEeeeeeeeeEeEEEABcdeEEeEeeEEEEeeEe

At present, such links lead to nowhere, and there's no way to link to the existing "add owner" or "replace owner" transaction modal.

The link is generated by the mobile app.

Original issue: safe-global/safe-ios#3096