This adds the ability to utilize sigv4 signing for all AWS services not
just "aps". When the newly introduced property "service" is not set it
will default to "aps".
Signed-off-by: Boris Petersen <boris.petersen@idealo.de>
* {lib/promscrape,app/vmagent}: adds sigv4 support for vmagent remoteWrite
moves aws related code into separate lib from lib/promscrape
it allows to write data from vmagent to the AWS managed prometheus (cortex)
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1287
* Apply suggestions from code review
* wip
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
