Can we do the unbreaking part of this work now and save the breaking part for a future 2.0 release?

I removed the breaking changes.

Sorry about this.
I got carried away because all tests and linting were passing;
This must be dropped and the changes in a previous PR about reducing any usage that changed
<T extends any[]> func ( ...args T> to func (...args: unknown[])
and
<C extends UserDatabaseClient> func (TransactionContext<C>) to func (TransactionContext<UserDatabaseClient>)
were a mistake and have to be reverted.

This declaration

type Func<T extends unknown[]> = (a: string, ...args: T) => void;

allows to define an implementation like the following which declares more than it should

const FuncImpl: Func<[number]> = (a: string, b: number) =>{}

BUT

type Func2 = (a:string ...args: unknown[]) => void;

does not allow do declare

const Func2Impl: Func2 = (a: string, b: number) => {}

BUT only

const Func2Impl: Func2 = (a: string, b: unknown) => {}

which is terrible.

As I realize now the proper way to define a function that takes any number of arguments is

type Func = (a: string ...any[]) => void

and it is safe since as it only declares that this is a function that must have a string argument and can take any number of additional arguments.

I will prepare a PR later that reverts all the affected code by #448.

Sorry again.
Typescript is a pain sometimes ....