Support KSP (Kotlin Symbol Processing)

Currently ObjectBox supports using KAPT for processing annotations in Kotlin.
KSP is a new Kotlin annotation processing framework by Google and supported by Jetbrains that processes annotations in a far more 'native' way than KAPT, resulting in improved performance and an API more suited for Kotlin. Consequently, KAPT has lost its focus from the Kotlin team (source).
ObjectBox should seriously consider providing an implementation for processing annotations in Kotlin using KSP. For reference, see this recent build time analysis:

A whopping 75.8% (24.2 seconds) of build time is spent on generating KAPT stubs, which supposedly KSP avoids completely. On the other hand, it appears only 0.8 seconds is spent doing actual Objectbox work.

Further reading:
What is KSP?
Why KSP?
KSP Github

该 issue 未指定任何仓库文件、测试或入口点。首先研究链接的 KSP 文档和现有的 KAPT 集成，然后将完成标准定义为通过 KSP 实现等效的 ObjectBox 注解处理，并验证构建时行为和生成代码的行为。