redis: use UniveralClient, support sentinel mode

This commit switches the redis client to using a UniversalClient [1],
which can operate in standard, cluster, or failover (sentinel) mode.

It also implements basic support for having (multiple)
`redis+sentinel://` URLs as connection URL in the config (e.g. for
`redis-host`).

This is the Go equivalent of the proposed Python patch [2]. It supports
the same examples given there.

[1] https://pkg.go.dev/github.com/go-redis/redis/v8#UniversalClient
[2] https://lists.sr.ht/~sircmpwn/sr.ht-dev/patches/55521

email: update StartTLS usage per go-smtp changes

Drop gqlparser v1 dependency

Only use v2 throughout the repository.

Migrate to chi v5

v1 is not maintained anymore.

Upgrade dependencies

s3: Import middleware from pages.sr.ht

Closes: https://todo.sr.ht/~sircmpwn/pages.sr.ht/19

go mod tidy

Fixes the following error when running `go test`:

    ../../go/pkg/mod/github.com/prometheus/client_golang@v1.14.0/prometheus/internal/metric.go:19:2: missing go.sum entry for module providing package github.com/prometheus/client_model/go (imported by github.com/prometheus/client_golang/prometheus); to add:
    	go get github.com/prometheus/client_golang/prometheus@v1.14.0

Add prometheus SQL connection stats

Also updates the prometheus client_go library

Update pq (Postgres driver) to latest version

Replace x/crypto package by ProtonMail/go-crypto to support ed25519 OpenPGP keys

Add support for mail setups that don't support TLS or Auth

auth: fix /query/api-meta.json route

This route does not need authentication.

Update go-bare

Update dependencies

Sign outgoing emails

Update dowork

Add legacy webhooks worker implementation

Expand context for work queues

Simplify server module

Add email work queue