This change updates the project structure to become flattened.
Previously, the simulator, frontend and API each lived into their own
directory.

With this change, all modules of the project live in the top-level
directory of the repository. This should improve discoverability of
modules of the project.

This change integrates the OpenTelemetry Metrics API in the OpenDC
Compute Service implementation. This replaces the old infrastructure for
gathering metrics.

This change removes the opendc-core module. This module was an artifact
of the old codebase and remained mostly unused. This change removes all
usages of the module and if necessary introduces replacement classes.

This change uses the Java Platform functionality from Gradle to enable
shared dependency constraints across modules.

This change updates the Gradle configuration to utilize version
constraints to force the same dependency version across modules.

This change moves the version of the dependencies from buildSrc to
gradle.properties to prevent recompilation when changing dependency
versions.

This change extracts the configuration for test from the Kotlin library
conventions.

This change eliminates the large Spark dependencies from the web runner.
Instead, we perform on the fly aggregation of the data and report
directly to MongoDB.