The `HardwareKeyringTypes` constant has been renamed to `KeyringTypes`
and moved to a separate constants module, to reflect that it contains
more than just hardware wallet keyring types. This corrects a mistake
made recently during a TypeScript conversion.
The `assert` module has two modes: "Legacy" and "strict". When using
strict mode, the "strict" version of each assertion method is implied.
Whereas in legacy mode, by default it will use the deprecated, "loose"
version of each assertion.
We now use strict mode everywhere. A few tests required updates where
they were asserting the wrong thing, and it was passing beforehand due
to the loose matching.
