Merge #3523 #3524

3523: Remove the so-called "pointless" tests from `Api.TypesSpec`. r=jonathanknowles a=jonathanknowles

## Issue Number

None.

## Description

This PR removes the so-called "pointless" tests from `Api.TypesSpec`.

## Justification

It's not clear what real value these tests provide, if any.

Of course, they do allow us to artificially increase our coverage from the point of view of the code coverage checker. But it's not clear why we should want to do this.

Moreover, artificially increasing the coverage score in this way may hide real gaps in test coverage: because of these "pointless" tests, our code coverage report currently can't tell us which types are really exercised by our test suite, and which are not.

Additionally, the set of types tested here is **_incomplete_**: many newer types were never added to the list.

If we really need to have this kind of test, then instead of maintaining these test definitions manually (a process that is error prone, requires a lot of boilerplate, and increases review overhead), it would be better to generate them automatically: then we can automatically cover all types used in the API, rather than just an subset.

However, if our goal is to reach 100% coverage of all API record field accessors, perhaps it would be better to focus our efforts on writing meaningful tests that actually stimulate the API.

3524: Document minimum UTxO behaviour in OpenAPI specification. r=jonathanknowles a=jonathanknowles

## Issue Number

ADP-2250

## Description

This PR adds documentation to the OpenAPI specification to describe how the wallet software handles minimum UTxO values.

Co-authored-by: Jonathan Knowles <[email protected]>