Benchmark to measure startup time

[JaroslavTulach]

Pull Request Description

While trying to speed MetadataStorage up - #8324 - I felt the need to have an independent (on my computer) measurement of startup time. Here is a benchmark that measures how long execution of two simple hello world programs take.

Important Notes

There are two benchmarks:

• empty_startup measures the time needed to boot without using any Standard library - basically an overhead of the JVM and engine
• hello_world_startup measures the use of IO.println - it shall take longer than empty_startup and show the overhead we have while processing the standard library

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• All code follows the
  style guides.
• All code has been tested:
  • Benchmarks have been executed.

[Akirathan]

Interesting benchmark. It would be nice to have it under engine benchmarks in Java, but fetching the enso executable in Java is cumbersome. This is better solution for now.