Establish configuration hierarchy. CLI args override `config.yaml`

generating a new server config has a hard switch between args or a static file:
```go
func GetServerConfig(dEnv *env.DoltEnv, apr *argparser.ArgParseResults) (ServerConfig, error) {
if cfgFile, ok := apr.GetValue(configFileFlag); ok {
return getYAMLServerConfig(dEnv.FS, cfgFile)
}
return getCommandLineServerConfig(dEnv, apr)
}
```

If the config file is passed and cli args aren't empty, apply the overrides to the server config.