* optimized parse cli's disabledMetrics flag string to initTelemetry

* add splitTrim to obtain string slice that not contain empty string

* change TestSplitTrim error output

* gofmt for run_test.go

* restore name of disabledMetrics made more sense

* optimized TestSplitTrim case

* just update splitTrim comment to force CI restart

By using option ca_certificates in proxy block it is possible now to select
CA against which backend certificates shall be checked.

Resolves #1550
Co-authored-by: Danny Navarro <navdgo@gmail.com>

* caddytls: Fix empty SNI handling (new -default-sni flag)

vendor: update certmagic, needed to support this

Hopefully fixes #2451, fixes #2438, and fixes #2414

* caddytls: Don't overwrite certmagic Manager (fixes #2407)

Supersedes #2447

* vendor: Update certmagic to fix nil pointer deref and TLS-ALPN cleanup

* Improve -default-sni flag help text

Other methods are not currently implemented in the static file server

* spelling: access

* spelling: associated

* spelling: because

* spelling: characteristics

* spelling: chooses

* spelling: cleared

* spelling: clustering

* spelling: collaborators

* spelling: connection

* spelling: content

* spelling: conversion

* spelling: deferring

* spelling: detection

* spelling: displayed

* spelling: dispenser

* spelling: heuristic

* spelling: nonexistent

* spelling: oflisting

* spelling: preparses

* spelling: response

* spelling: responder

* spelling: sensitive

* spelling: specify

* spelling: simple

* spelling: spawning

* spelling: status

* spelling: unsupported

* spelling: upstream

* spelling: username

* spelling: whether

For log and errors directive, as well as process log.

Execute an OPTIONS call and make sure we receive a valid response
independently of the provided username or password as the
authentication step is ignored

* Do not authenticate OPTIONS calls
* Add test for OPTIONS call

Add header X-Forwarded-Port to preset transparent

Closes #2356

* caddy: move EmitEvent(InstanceStartupEvent, instance)

* caddy: update SupportedEvents

A tls.Config must have Certificates or GetCertificate set, in order to
be accepted by tls.Listen and quic.Listen.

Implement `{when_iso_local}` placeholder

This implements the `{when_iso_local}` placeholder. This is like the
`{when_iso}` placeholder but the output is in the current timezone
rather than UTC.

Resolves #2362