Rewrite the Generate Endpoints script

[EmmmaTech]

Overview of the Feature Request
Rewrite the generate endpoints script, renaming it to generate_routes.py, rename the data/endpoints folder to data/routes, and change the type of the files used in data/routes from JSON to TOML.

What is this Feature Request for?
DisCatCore

The Problem
The generate endpoints script needs a good code scrub. There are some things that could be done better or just completely removed, like the function generator's generate method. Also the function generator's methods for managing arguments can be removed in favor of the publicly available list of args. There might be more, and they'll be seen in my PR.

Now to the name changes. Since the beginning of the endpoint generator, I thought that the name "endpoint" sounded more appropriate and did not consider the name "route" at all. The name "route" is used for the HTTP client to specify the metadata about a Discord API route. It makes more sense to name our endpoint generate a route generator since the route wrappers generated wrap Discord API routes (obviously).

Finally, the file change. JSON is unreadable for our purposes.. TOML would be a better format, since it's designed to be a config file format and human readable.

The Solution
Here's what a new route file under TOML will look like:

name = "UserRoutes"
requires = ["typing", "discord_typings"]

[get_current_user]
method = "GET"
url = "/users/@me"

[get_user]
method = "GET"
url.link = "/users/{user_id}"
url.parameters = [{name = "user_id", type = "dt.Snowflake"}]

[modify_current_user]
method = "PATCH"
url = "/users/@me"
json.parameters = [
    {name = "username", type = "UnsetOr[str]", default = "Unset"},
    {name = "avatar", type = "UnsetOr[t.Optional[str]]", default = "Unset"},
]

[get_current_user_guilds]
method = "GET"
url.link = "/users/@me/guilds"
url.parameters = [
    {name = "before", type = "UnsetOr[dt.Snowflake]", default = "Unset"},
    {name = "after", type = "UnsetOr[dt.Snowflake]", default = "Unset"},
    {name = "limit", type = "int", default = "200"},
]

Current Solution
N/A

Additional context
N/A