* Async API improvements "v2"
**NB: This PR actually changes only 3 files in `libraries/architecture/`. All the other changes are automated refactors to fix the calling code.**
This is a proposal for improvements to our `Async` type as discussed in: https://github.com/vector-im/element-x-android/pull/598/files#r1230664392 and in other chats.
Please bear in mind it is just a proposal, I'd love to hear your feedback about it, especially when it comes to naming: I've tried to make parameter and function names use a terminology similar to what we find in the Kotlin stdlib and its `Result` type.
I'm inclined to like more the non-extension flavours of the new `run*` APIs, though I'd also like your feedback about what API shape you prefer.
### Summary of the changes:
#### Functional
- Adds `exceptionOrNull()` API to complement the existing `dataOrNull()` API.
- Adds `isFailure()`, `isLoading()`, `isSuccess()` and `isUninitialized()` courtesy APIs.
- Renames `executeResult()` to `runUpdatingState()`:
- Becomes the base API to which all the other similarly named APIs call into.
- Makes it inline.
- Adds contract.
- Passes over any `prevData` to newre Async states.
- Passes through the `block`s return value.
- Adds unit tests.
- Renames `execute` to `runCatchingUpdatingState()` and makes it just call into `runUpdatingState()`
- Adds extension function overloads to the `run*` functions to accept `MutableState` as receiver
#### Cosmetics
- Reorders classes and methods in alphabetic order.
- Reorder parameter names to mimic conventions in Kotlin stdlib.
- Adds docstrings where useful.
* Use `fold()`
* rename pop to popFirst
* Add docstrings
* Please Detekt
* Rename exception to error.
* Please detekt
* Update existing usages.
Benoit Marty