Upgrade to GraalVM JDK 21.
```
> java -version
openjdk version "21" 2023-09-19
OpenJDK Runtime Environment GraalVM CE 21+35.1 (build 21+35-jvmci-23.1-b15)
OpenJDK 64-Bit Server VM GraalVM CE 21+35.1 (build 21+35-jvmci-23.1-b15, mixed mode, sharing)
```
With SDKMan, download with `sdk install java 21-graalce`.
# Important Notes
- After this PR, one can theoretically run enso with any JRE with version at least 21.
- Removed `sbt bootstrap` hack and all the other build time related hacks related to the handling of GraalVM distribution.
- `project-manager` remains backward compatible - it can open older engines with runtimes. New engines now do no longer require a separate runtime to be downloaded.
- sbt does not support compilation of `module-info.java` files in mixed projects - https://github.com/sbt/sbt/issues/3368
- Which means that we can have `module-info.java` files only for Java-only projects.
- Anyway, we need just a single `module-info.class` in the resulting `runtime.jar` fat jar.
- `runtime.jar` is assembled in `runtime-with-instruments` with a custom merge strategy (`sbt-assembly` plugin). Caching is disabled for custom merge strategies, which means that re-assembly of `runtime.jar` will be more frequent.
- Engine distribution contains multiple JAR archives (modules) in `component` directory, along with `runner/runner.jar` that is hidden inside a nested directory.
- The new entry point to the engine runner is [EngineRunnerBootLoader](https://github.com/enso-org/enso/pull/7991/files#diff-9ab172d0566c18456472aeb95c4345f47e2db3965e77e29c11694d3a9333a2aa) that contains a custom ClassLoader - to make sure that everything that does not have to be loaded from a module is loaded from `runner.jar`, which is not a module.
- The new command line for launching the engine runner is in [distribution/bin/enso](https://github.com/enso-org/enso/pull/7991/files#diff-0b66983403b2c329febc7381cd23d45871d4d555ce98dd040d4d1e879c8f3725)
- [Newest version of Frgaal](https://repo1.maven.org/maven2/org/frgaal/compiler/20.0.1/) (20.0.1) does not recognize `--source 21` option, only `--source 20`.
- Previous GraalVM update: https://github.com/enso-org/enso/pull/6750
Removed warnings:
- Remove deprecated `ConditionProfile.createCountingProfile()`.
- Add `@Shared` to some `@Cached` parameters (Truffle now emits warnings about potential `@Share` usage).
- Specialization method names should not start with execute
- Add limit attribute to some specialization methods
- Add `@NeverDefault` for some cached initializer expressions
- Add `@Idempotent` or `@NonIdempotent` where appropriate
BigInteger and potential Node inlining are tracked in follow-up issues.
# Important Notes
For `SDKMan` users:
```
sdk install java 17.0.7-graalce
sdk use java 17.0.7-graalce
```
For other users - download link can be found at https://github.com/graalvm/graalvm-ce-builds/releases/tag/jdk-17.0.7
Release notes: https://www.graalvm.org/release-notes/JDK_17/
R component was dropped from the release 23.0.0, only `python` is available to install via `gu install python`.
