Kotlin api/language backwards compatibility

[JakeWharton]

We want the newest Kotlin but the lowest api/language compatibility.

External requests:

• 1.14 isn't compatible with Gradle 8.12 cashapp/licensee#497
• Retrofit 3.0.0 and 2.12.0 Kotlin compatibility issue with Spring Boot 3.4.5 (Kotlin 1.9.25) square/retrofit#4381
• Incompatible Kotlin Version Error with OkHttp v5.1.0 square/okhttp#9032
• Set apiVersion and languageVersion to 2.0 for backwards compatibility square/okio#1690

Projects:

• JakeWharton/cite
• JakeWharton/confundus
  • Add Tapmoc for compatibility and test minimum Gradle version confundus#94
• JakeWharton/crossword
• JakeWharton/diffuse
• JakeWharton/finalization-hook
• JakeWharton/kmp-missing-targets
  • Validate compatibility kmp-missing-targets#122
• JakeWharton/mosaic
• JakeWharton/picnic
• JakeWharton/test-distribution-gradle-plugin
  • Use Tapmoc for compatibility, test full range test-distribution-gradle-plugin#51
• JakeWharton/timber
  • Remove explicit JVM toolchain, add Java 8/Kotlin 2.0 compatibility timber#590
• cashapp/burst
• cashapp/copper
• cashapp/licensee
  • Manual revert of compatibility back to Gradle 8.12 cashapp/licensee#500
• cashapp/molecule
• cashapp/paraphrase
• cashapp/turbine
• cashapp/zipline
• SQLDelight/Grammar-Kit-Composer
• SQLDelight/sql-psi
• SQLDelight/SQLDelight
• square/kotlinpoet
• square/moshi
• square/okio
• square/okhttp
• square/retrofit
• square/wire
• square/zstd-kmp