Add utils.basic_autocomplete

[BobDotCom]

Summary

Adds a basic autocomplete function to utils. Usage:

import discord
from discord import option
from discord.utils import basic_autocomplete

bot = discord.Bot()

@bot.slash_command()
@option("color", autocomplete=basic_autocomplete(["red", "orange", "yellow", "green", "blue", "purple", "red-orange"]))
async def test_color(ctx, color):
    await ctx.respond(f"Your choice: {color}")
    
async def autocomplete(interaction):
    return [str(num) for num in range(1, len(interaction.user.display_name))]

@bot.slash_command()
@option("number", autocomplete=basic_autocomplete(autocomplete))
async def test_number(ctx, number):
    await ctx.respond(f"Your choice: {number}")

Checklist

• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed)
• This PR is not a code change (e.g. documentation, README, typehinting, ...)

[Lulalaby]

LGTM