Finishes [CSDK-451].
This new small public API allows users to quickly figure out if everything in the SDK is correctly configured in a simple way:
```swift
let tester = SDKTester.default
do {
  try await tester.test()
} catch {
  print(error)
}
```

The specific underlying errors will provide information about what failed.

We can continue growing this to check for more specific things, but for now it does 4 things:
- Verify API connectivity: networking issues, firewalling, etc.
- Verify API key is correct
- Verify `Offerings` are configured correctly
- Verify that all products in `Offerings` are configured correctly and found in `StoreKit`

This new API is covered by:
- API testers
- Unit tests
- Integration tests (both on `SK1` and `SK2`)

- #1970
- #1971
- #1973
- #1974
- #1975
- #1976

Finishes [CSDK-451].
This new small public API allows users to quickly figure out if everything in the SDK is correctly configured in a simple way:
```swift
let tester = SDKTester.default
do {
  try await tester.test()
} catch {
  print(error)
}
```

The specific underlying errors will provide information about what failed.

We can continue growing this to check for more specific things, but for now it does 4 things:
- Verify API connectivity: networking issues, firewalling, etc.
- Verify API key is correct
- Verify `Offerings` are configured correctly
- Verify that all products in `Offerings` are configured correctly and found in `StoreKit`

This new API is covered by:
- API testers
- Unit tests
- Integration tests (both on `SK1` and `SK2`)

- #1970
- #1971
- #1973
- #1974
- #1975
- #1976

**This is an automatic release.**

### Bugfixes
* Fixed Xcode 13.2.x / Swift 5.5 compatibility (#1994) via NachoSoto
(@NachoSoto)
### Other Changes
* Update `fastlane` (#1998) via NachoSoto (@NachoSoto)
* Documentation: fixed missing docs from inherited symbols (#1997) via
NachoSoto (@NachoSoto)
* CI: added job to test compilation with `Xcode 13.2.1` / `Swift 5.5`
(#1990) via NachoSoto (@NachoSoto)
* Extracted `TrialOrIntroPriceEligibilityCheckerType` (#1983) via
NachoSoto (@NachoSoto)
* CI: removed redundant `swiftlint` installation (#1993) via NachoSoto
(@NachoSoto)
* `Nimble`: use a fixed version (#1991) via NachoSoto (@NachoSoto)
* Update fastlane-plugin-revenuecat_internal (#1989) via Cesar de la
Vega (@vegaro)
* `Purchases.logIn`: log warning if attempting to use a static
`appUserID` (#1958) via NachoSoto (@NachoSoto)
* Created `InternalAPI` for "health" request (#1971) via NachoSoto
(@NachoSoto)

Co-authored-by: RCGitBot <dev+RCGitBot@revenuecat.com>

Finishes [CSDK-451].
This new small public API allows users to quickly figure out if everything in the SDK is correctly configured in a simple way:
```swift
let tester = SDKTester.default
do {
  try await tester.test()
} catch {
  print(error)
}
```

The specific underlying errors will provide information about what failed.

We can continue growing this to check for more specific things, but for now it does 4 things:
- Verify API connectivity: networking issues, firewalling, etc.
- Verify API key is correct
- Verify `Offerings` are configured correctly
- Verify that all products in `Offerings` are configured correctly and found in `StoreKit`

This new API is covered by:
- API testers
- Unit tests
- Integration tests (both on `SK1` and `SK2`)

- #1970
- #1971
- #1973
- #1974
- #1975
- #1976

…errors (#1977)

Finishes [CSDK-451].

This new small public API allows users to quickly figure out if
everything in the SDK is correctly configured in a simple way:
```swift
let diagnostics = PurchasesDiagnostics.default
do {
    try await diagnostics.testSDKHealth()
} catch {
    print(error)
}
```

The specific underlying errors will provide information about what
failed.

We can continue growing this to check for more specific things, but for
now it does 4 things:
- Verify API connectivity: networking issues, firewalling, etc.
- Verify API key is correct
- Verify `Offerings` are configured correctly
- Verify that all products in `Offerings` are configured correctly and
found in `StoreKit`

This new API is covered by:
- API testers
- Unit tests
- Integration tests (both on `SK1` and `SK2`)

_I've taken the "shortcut" of making this `async` only (while still
compatible with Objective-C), which means it's not compatible with iOS
12.x. But that made the implementation a lot simpler, which I think is a
useful tradeoff._

### Depends on:
- #1970
- #1971
- #1973
- #1974
- #1975
- #1976

[CSDK-451]:
https://revenuecats.atlassian.net/browse/CSDK-451?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ