Adds an existing module to be used with @import.
pub fn addImport(m: *Module, name: []const u8, module: *Module) void
pub fn addImport(m: *Module, name: []const u8, module: *Module) void {
const graph = m.owner.graph;
const arena = graph.arena;
m.import_table.put(arena, graph.dupeString(name), module) catch @panic("OOM");
}