perf: improve FrankenPHP config

[dunglas]

Expanded, the current config is similar to this:

# Add trailing slash for directory requests
@canonicalPath {
	file {path}/index.php
	not path */
}
redir @canonicalPath {path}/ 308
# If the requested file does not exist, try index files
@indexFiles file {
	try_files {path} {path}/index.php index.php
	split_path .php
}
rewrite @indexFiles {http.matchers.file.relative}
# FrankenPHP!
@phpFiles path *.php
php @phpFiles
file_server

I recently took some time to profile and optimize FrankenPHP, and that config is the slowest part in FrankenPHP (this likely affects the php_fastcgi Caddy directive as well). All the calls to try_files and file do I/O operations, which are slow.
Most of these I/O operations are checks useful for traditional PHP apps where the document root contains a lot of .php files (like WordPress) but are not needed when using Symfony or Laravel.

This simplified config reduces the number of I/O to the strict minimum: just 1 check to see if the requested path exists on disk, and delegates to PHP if it's not the case.

In the future, I plan to add a framework subdirective to php_server that automatically generates this config.

cc @francislavoie, this may also be interesting for php_fastcgi.

[maxhelias]

Thanks @dunglas !
The latest FrankenPHP optimizations are a remarkable and impressive piece of work.