This change removes the dependency on the OpenTelemetry SDK. Instead,
we'll only expose metrics via the OpenTelemetry API in the future via
adapter classes.

This change introduces a `ComputeMetricReader` class that can be used as
a replacement for the `CoroutineMetricReader` class when reading metrics
from the Compute service. This implementation operates directly on a
`ComputeService` instance, providing better performance.

This change updates the OpenDC codebase to use OpenTelemetry v1.11,
which stabilizes the metrics API. This stabilization brings quite a few
breaking changes, so significant changes are necessary inside the OpenDC
codebase.

This change updates the Clock adapter for OpenTelemetry to return the
current time in nanoseconds as specified by the method contract (as
opposed to milliseconds).

This change updates the CoroutineMetricReader to ensure that the
exporter is shutdown when the metric reader fails or is shutdown.

This change standardizes the metrics emitted by SimHost instances and
their guests based on the OpenTelemetry semantic conventions. We now
also report CPU time as opposed to CPU work as this metric is more
commonly used.

This change simplifies the CoroutineMetricReader implementation by
removing the seperation of reader and exporter jobs.

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.