Increase flow type coverage

[rdig]

Right now the projects's type coverage hovers somewhere around 65-70%.

I want this to go over 80%.

While this is not a big hurdle, in the interest of time, this is not a priority and will be backlogged (until all wallet types are implemented)

Also, this should add a flow coverage reporter (eg: flow-coverage-report) and set that up as a CI step.