Add start/end time and duration information to BEP messages

### Description of the feature request:

BEP messages don't currently include timestamps on per-action start/completed events, nor the duration of the action in the completion event. This information is not currently in the [proto](https://github.com/bazelbuild/bazel/blob/master/src/main/java/com/google/devtools/build/lib/buildeventstream/proto/build_event_stream.proto#L544), and would be important for us to use BEP events to analyze the behavior of our builds so we can summarize the results to the scripts that invoke Bazel.

### Which category does this issue belong to?

_No response_

### What underlying problem are you trying to solve with this feature?

Allow on-host analysis of our builds as they execute, so we can summarize those results to the scripts that invoke Bazel and provide feedback about the state of the build as it executes, without requiring us to process files (e.g. command.profile.gz) that are only created when the build finishes.

### Which operating system are you running Bazel on?

_No response_

### What is the output of `bazel info release`?

_No response_

### If `bazel info release` returns `development version` or `(@non-git)`, tell us how you built Bazel.

_No response_

### What's the output of `git remote get-url origin; git rev-parse master; git rev-parse HEAD` ?

_No response_

### Have you found anything relevant by searching the web?

_No response_

### Any other information, logs, or outputs that you want to share?

_No response_