Document mono package, support Unix and Parse.

[dennwc]

This is a proposal to clarify usage of the mono package. The change adds some basic docs as well as some extra API and deprecations.

A few proposed changes:

• Document that using time.Now() is fine, there's no need to use mono.Now(). Go's time is already monotonic.
• Use time.Now() directly in mono.Now(). There shouldn't be a need for getting relative time from the reference.
• Discourage direct use of mono.FromTime. Introduce mono.Unix(sec,ns) and mono.Parse instead. Most non-monotonic timestamps come from these two functions.

In addition, we should probably add a static check to CI for core and media repos to catch remaining usages of time.Unix and time.Parse. These must be updated to corresponding mono function calls. This should be easier than tracking down all non-monotonic timestamps across the codebase.

[changeset-bot]

🦋 Changeset detected

Latest commit: 8c7fa05

The changes in this PR will be included in the next version bump.

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

💥 An error occurred when fetching the changed packages and changesets in this PR

Some errors occurred when validating the changesets config:
The package or glob expression "github.com/livekit/protocol" specified in the `fixed` option does not match any package in the project. You may have misspelled the package name or provided an invalid glob expression. Note that glob expressions must be defined according to https://www.npmjs.com/package/micromatch.

[boks1971]

lgtm! Good call on doing a sweep for time.Unix and time.Parse usage