LSP: automatically initiate Meson Build System to provide server initialization/configuration
Currently server is initialized without any configuration by the client, the configuration is sent when the server request it, but that means the initialization doesn't provide the required bits to generate the required information to allow the server to serve correct responses.
SDK provides the required packages by the project, so it should be used to generate the correct configuration; while when using Meson Build System, that information is not available until it is initiated, so the server should be initialized with the initiated build system introspection; so when Meson Build System is in use, Builder should start build system initialization process, automatically at project load and before to start a client or notify configuration change when that initialization has been successful.
Pipeline has a STARTED signal, but a INITIATED signal should be present allowing the user to initiate the build system; and the plugin can be connected to it in order to send configuration change notification to the server.
Allowing the Client to provide its initialization configuration, will help to avoid autoconfiguration generation when the server supports it, like in GVls, so just when the configuration is ready a configuration change notification is sent the one required by the server.
If Builder loads a project and starts immediately the build system initialization, sending the INITIATED signal, the plugin can connect to it and differ server initialization until the build system can provide the required information to generate server configuration; but again Builder should be able plugins to provide server configuration at initialization stage.