[SSDK-736] fix SDK import through SPM

[aokj4ck]

Description

Fixes SSDK-736

• This fixes a "SILFunction type mistmatch" when using SPM and Xcode 15.3.
• More on SILFunction type mismatch: SILFunction type mismatch swiftlang/swift#65849

I'm asking because @_implementationOnly is only compatible with resilient modules. You can build resilient modules using a classic Xcode project and by enabling the build setting Build Library for Distribution. I believe packages don't yet have a way to enable this feature without using unsafe flags.

Using @_implementationOnly without resilience may lead to runtime crashes and memory corruption. Very recent compilers warn about this configuration.

Considering @_implementationOnly is an unofficial feature you may still hit compiler crashes even in supported configurations. While there's not much we can do for crashes without resilience, if you still see a crash after enabling resilience I may be able to help on that front.

Checklist

• Update CHANGELOG

[azarovalex]

Makes me think, @ _implementationOnly isn't the only experimental attribute we use, there is also @_exported: https://github.com/search?q=repo:mapbox/mapbox-search-ios%20_exported&type=code

Dropping it would be a breaking change because all developers will have to add additional imports, so I guess we can leave it for now.

[aokj4ck]

Yeah that @_exported inside MapboxSearchController is very convenient to automatically import MapboxSearch. Stay tuned as the language evolves.