Settings that have an RWS_CONFIG_* variable but no command-line flag.
In rws.config.toml they’re written like any other key — the variable
name is the table path plus key, upper-cased: [rate_limit] max_requests
→ RWS_CONFIG_RATE_LIMIT_MAX_REQUESTS. Settings that do have a flag are
taken from CommandLineArgument::get_command_line_arg_list() instead.
tests.rs checks this list against every RWS_CONFIG_* name in src/.
Load rws.config.toml into the environment: filepath (relative to the
working directory) when given, else the file named by RWS_CONFIG_FILE
(absolute, or relative to the working directory) — the same variable
proxy_config reads routes from — else rws.config.toml in the working
directory.
Apply every setting in a rws.config.toml document to the process
environment (see collect_settings). Unknown keys are reported on
stderr instead of being ignored silently.