make key_value.lix_server_url always defined

[samuelstroschein]

Context

Ran into a bug because i was updating lix_server_url instead of insert on conflict update

await Promise.all(
		[lixA, lixB].map((lix) =>
			lix.db
				.updateTable("key_value")
				.where("key", "=", "lix_server_url")
				.set({ value: "http://mock.com" })
				.execute(),
		),
	);

Proposal

Make lix_server_url always defined as JSON where either a URL is given or the value is null.

• avoid insert, on conflict logic