[surfacers.otel] Allow adding a prefix to metric names. (cloudprober#658

)

- Default prefix is cloudprober_.
- This is important to identify cloudprober metrics on the final
metrics system.

[prober] Minor refactoring. (cloudprober#625)

- Use read-write mutex, instead of regular mutex, to control access to cloudprober config info.
- Get raw and parsed config from the config source directly instead of storing it ahead of time.
- Allow access to the prober instance.

[logger] Streamline logger interface. (cloudprober#542)

- Rename old New function to NewLegacy. This function is now deprecated.
- Add a new, simpler, New function that takes only optional arguments.

[docs] Share Cloudprober's journey through an About page. (cloudprobe…

…r#439)

* Add blog-meta shortcode to add blog-like metadata for such pages.

[oauth2] Fix a bug in HTTP token refresh. (cloudprober#422)

* While fixing the HTTP request body handling in [probes.http] Fix HTTP request body handling. cloudprober#408, I introduced a bug: that PR changed request body to be buffered all the time to simplify it. I missed changing oauth2.http_token at that time. This PR fixes that.
* Improve tests.

[probes.external] Improve the startCmdIfNotRunning test further. (clo…

…udprober#398)

* Verify that we restart the command when it stops (pause=0).

Older website design.

Update getting-started.md

Update docker image path to Github container registry.

[probes.http] Don't overwrite server_name if set in tls_config (cloud…

…prober#294) (cloudprober#295)

[probe.http] Add an option to limit redirects (cloudprober#289)

Co-authored-by: Rob Pickerill <[email protected]>