refactor(memmap): fix typing-related issues

This change introduces Pyright - a static type checker for Python - and
resolves a large number of the errors that it reports. Some errors have
not been resolved as they require larger refactors, so these will be
done in later patches.

Change-Id: I2ed9b1cc729bf44a1fa8e69882af34657cc30b38
Signed-off-by: Chris Kay <chris.kay@arm.com>
6 files changed