Snapshots: move some of the bootstrap options from runtime to snapshot time

[bartlomieju]

We have following data that needs to be sent over to the runtime during bootstrapping:

deno/runtime/worker_bootstrap.rs

Lines 109 to 148 in 9010b8d

	struct BootstrapV8<'a>(
	// args
	&'a Vec<String>,
	// cpu_count
	i32,
	// log_level
	i32,
	// runtime_version
	&'a str,
	// locale
	&'a str,
	// location
	Option<&'a str>,
	// no_color
	bool,
	// is_tty
	bool,
	// ts_version
	&'a str,
	// unstable
	bool,
	// granular unstable flags
	&'a [i32],
	// process_id
	i32,
	// env!("TARGET")
	&'a str,
	// v8_version
	&'a str,
	// user_agent
	&'a str,
	// inspect
	bool,
	// enable_testing_features
	bool,
	// has_node_modules_dir
	bool,
	// maybe_binary_npm_command_name
	Option<&'a str>,
	);

Some of this data is fixed for a particular build of Deno, namely:

• runtime_version
• ts_version
• env!("TARGET")
• v8_version
• user_agent

All of these are strings which are the most expensive stuff to serialize on bootstrap. Moving them to be defined only once during snapshot should help us (although minimally) to improve the startup time.