Add build_info data

[keturiosakys]

Resolves #45

This update adds build_info data to the metrics exported. Whenever the first
autometrics wrapper is called it will create an object that will persisting
through the runtime and report version, commit, and branch data (depending on
what is supplied). The data can be supplied through env variables:

version: picked up automatically if the package is run through npm, yarn, or
pnpm, - can be manually supplied through PACKAGE_VERSION or AUTOMETRICS_VERSION otherwise.

commit: must be supplied through COMMIT_SHA or AUTOMETRICS_COMMIT env variable

branch: must be supplied through BRANCH_NAME or AUTOMETRICS_BRANCH env variable

The update also fixes a previous functionality that would throw an error if a
function without a name was supplied. It will now just log a warning and returns the
function early without attempting to instrument.

• replace error throw with a log
• add a way to register build_info data to the metrics

[brettimus]

btw i did this in python today if you want to compare notes

autometrics-dev/autometrics-py#35

[keturiosakys]

btw i did this in python today if you want to compare notes

autometrics-dev/autometrics-py#35

ah nice thanks! I updated the env variables to the same naming scheme

[oscarvz]

Apart from some code style nits, lgtm!