chore(packaging): Release pipeline

[sh0rez]

This PR adds an automated release pipeline. Proposed release process is the following:

• when PR's are merged, add a notice to the Unreleased section of CHANGELOG.md
• on release time, make sure master is in a good shape
• finish up CHANGELOG.md by adding the version number, commit and tag annotated
• CircleCI picks the tag up, adds binaries and some boilerplate release notes to a Draft release
• add free-form release notes, publish the release

Binaries are built for:

	Linux	Windows	macOS	FreeBSD
amd64	l, p, c	p, c	p, c	p, c
arm64	l, p, c	p, c	p, c	p, c
arm	l, p, c	p, c	p, c	p, c

l: Loki, p: Promtail. c: Logcli

Binaries are gzipped for performance reasons, the individual .gz files are sha256-hashed to verify the integrity

Closes #659