[Deps] Investigate ways of integrating ktfmt

[rami3l]

We're vendoring ktfmt (here) since it uses the embedded Kotlin compiler rather than the standard one, which we use. The embedded Kotlin compiler uses other package paths (e.g. org.jetbrains.kotlin.com.intellij instead of com.intellij), which causes weird clashes at runtime, for example:

java.lang.NoSuchMethodError: 'org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment$Companion.createForProduction(org.jetbrains.kotlin.com.intellij.openapi.Disposable, org.jetbrains.kotlin.config.CompilerConfiguration, org.jetbrains.kotlin.cli.jvm.compiler.EnvironmentConfigFiles)'
            at com.facebook.ktfmt.format.Parser.parse(Parser.kt:45)
            at com.facebook.ktfmt.format.Formatter.sortedAndDistinctImports(Formatter.kt:141)
            at com.facebook.ktfmt.format.Formatter.format(Formatter.kt:84)
            at org.javacs.kt.formatting.FormatterKt.formatKotlinCode(Formatter.kt:10)
            at org.javacs.kt.KotlinTextDocumentService$formatting$1.invoke(KotlinTextDocumentService.kt:204)
            at org.javacs.kt.KotlinTextDocumentService$formatting$1.invoke(KotlinTextDocumentService.kt:199)
            at org.javacs.kt.util.AsyncExecutor.compute$lambda-2(AsyncExecutor.kt:19)
            at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1700)
            at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
            at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
            at java.base/java.lang.Thread.run(Thread.java:829)

While this is non-ideal, it's currently the best solution I could find that works for our setup. A better solution would be to automate this as part of our Gradle build (i.e. rewrite the package paths and replace the transitive kotlin-compiler-embeddable dependency with kotlin-compiler - basically do this automatically), but I couldn't figure out a clean way of doing so yet.

Originally posted by @fwcd in #330 (comment)

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... there were other dependencies which needed the non-embedded compiler and didn't have an embedded version themselves (I think it was the kotlin-scripting-compiler or perhaps the IDEA plugin, which we no longer depend on though, can't remember).

Originally posted by @fwcd in #330 (comment)

[casret]

@fwcd can we update the vendored version, it's a couple years out of data at this point?