adjust code to more closely match documented semantics

Instead of hardcoding the arguments within the loader, pass them
through the searcher, as specified by the documented behavior:

#689 (comment)

> quoted from https://www.lua.org/manual/5.4/manual.html#pdf-require
>
>> Once a loader is found, require calls the loader with two arguments:
>> modname and an extra value, a loader data, also returned by the
>> searcher. The loader data can be any value useful to the module;
>> for the default searchers, it indicates where the loader was found.
>> (For instance, if the loader came from a file, this extra value is
>> the file path.)

Thanks @fperrad for the research!

tl.lua

@@ -5487,14 +5487,14 @@ local function init_globals(lax)
             }),
             ["loaders"] = a_type({
                typename = "array",
-               elements = a_type({ typename = "function", args = TUPLE({ STRING }), rets = TUPLE({ ANY }) }),
+               elements = a_type({ typename = "function", args = TUPLE({ STRING }), rets = TUPLE({ ANY, ANY }) }),
             }),
             ["loadlib"] = a_type({ typename = "function", args = TUPLE({ STRING, STRING }), rets = TUPLE({ FUNCTION }) }),
             ["path"] = STRING,
             ["preload"] = TABLE,
             ["searchers"] = a_type({
                typename = "array",
-               elements = a_type({ typename = "function", args = TUPLE({ STRING }), rets = TUPLE({ ANY }) }),
+               elements = a_type({ typename = "function", args = TUPLE({ STRING }), rets = TUPLE({ ANY, ANY }) }),
             }),
             ["searchpath"] = a_type({ typename = "function", args = TUPLE({ STRING, STRING, OPT(STRING), OPT(STRING) }), rets = TUPLE({ STRING, STRING }) }),
          },
@@ -10824,11 +10824,11 @@ local function tl_package_loader(module_name)
       local code = assert(tl.pretty_print_ast(program, env.gen_target, true))
       local chunk, err = load(code, "@" .. found_filename, "t")
       if chunk then
-         return function()
-            local ret = chunk(module_name, found_filename)
+         return function(modname, loader_data)
+            local ret = chunk(modname, loader_data)
             package.loaded[module_name] = ret
             return ret
-         end
+         end, found_filename
       else
          error("Internal Compiler Error: Teal generator produced invalid Lua. Please report a bug at https://github.com/teal-language/tl\n\n" .. err)
       end

tl.tl

@@ -5487,14 +5487,14 @@ local function init_globals(lax: boolean): {string:Variable}, {string:Type}
             },
             ["loaders"] = a_type {
                typename = "array",
-               elements = a_type { typename = "function", args = TUPLE { STRING }, rets = TUPLE { ANY } }
+               elements = a_type { typename = "function", args = TUPLE { STRING }, rets = TUPLE { ANY, ANY } }
             },
             ["loadlib"] = a_type { typename = "function", args = TUPLE { STRING, STRING }, rets = TUPLE { FUNCTION } },
             ["path"] = STRING,
             ["preload"] = TABLE,
             ["searchers"] = a_type {
                typename = "array",
-               elements = a_type { typename = "function", args = TUPLE { STRING }, rets = TUPLE { ANY } }
+               elements = a_type { typename = "function", args = TUPLE { STRING }, rets = TUPLE { ANY, ANY } }
             },
             ["searchpath"] = a_type { typename = "function", args = TUPLE { STRING, STRING, OPT(STRING), OPT(STRING) }, rets = TUPLE { STRING, STRING } },
          },
@@ -10791,7 +10791,7 @@ tl.gen = function(input: string, env: Env): string, Result
    return code, result
 end
 
-local function tl_package_loader(module_name: string): any
+local function tl_package_loader(module_name: string): any, any
    local found_filename, fd, tried = tl.search_module(module_name, false)
    if found_filename then
       local input = read_full_file(fd)
@@ -10824,11 +10824,11 @@ local function tl_package_loader(module_name: string): any
       local code = assert(tl.pretty_print_ast(program, env.gen_target, true))
       local chunk, err = load(code, "@" .. found_filename, "t")
       if chunk then
-         return function(): any
-            local ret = chunk(module_name, found_filename)
+         return function(modname: string, loader_data: string): any
+            local ret = chunk(modname, loader_data)
             package.loaded[module_name] = ret
             return ret
-         end
+         end, found_filename
       else
          error("Internal Compiler Error: Teal generator produced invalid Lua. Please report a bug at https://github.com/teal-language/tl\n\n" .. err)
       end