Feature Request: Save Arbitrary Path in Preferences

[ChristopherA]

As per feature request in discussion BlockchainCommons/Gordian#82:

Until we have a major upgrade for more types of blockchains, add an option in Preferences to name and save an arbitrary path as default. i.e. "Polygon" and "m/44'/966'/0'/0/0". It name will replace Bitcoin or Ethereum as the default the "Derive Key" pane, and the path will the the default.

Should test to confirm values with Polygon, Tezos, and a couple of other top blockchains that use BIP-44, and have @shannona document it.

[wolfmcnally]

This should probably be generalized to allowing the user to save a set of pre-defined paths they wish to use, and choose any of the built-in or pre-defined paths as the default.