Confusing that we have two functions `isValidAlias` and `isAliasFormat`, esp given that a string that `isAliasFormat` would fail `isValidAlias`.
This arose because we built the alias creation screen first, then, when implementing alias send features, decided that `.xec` should be included to avoid confusion with aliases on other chains.
Update the name of `isValidAlias` to be more specific. Refactor unit tests to match `vectors` approach.