This restores the FromAlert header to prometheus for Grafana managed alert Queries.
It does this by reverting "Prometheus: Remove middleware for custom headers (#51518)" , but also changing it so it is only the FromAlert header.
This reverts commit 2372501368.
* WIP
* Set public_suffix to a pre Ruby 2.6 version
* we don't need to install python
* Stretch->Buster
* Bump versions in lib.star
* Manually update linter
Sort of messy, but the .mod-file need to contain all dependencies that
use 1.16+ features, otherwise they're assumed to be compiled with
-lang=go1.16 and cannot access generics et al.
Bingo doesn't seem to understand that, but it's possible to manually
update things to get Bingo happy.
* undo reformatting
* Various lint improvements
* More from the linter
* goimports -w ./pkg/
* Disable gocritic
* Add/modify linter exceptions
* lint + flatten nested list
Go 1.19 doesn't support nested lists, and there wasn't an obvious workaround.
https://go.dev/doc/comment#lists
