Interactions.py

Merged 36.
Fixed errors related to guild ID.
Fixed unexpected behaviors related to commands and subcommands.

Merged 33.
Added proper Cog support.
Fixed subcommand can override previously added base command.
Changed slash command to the model.

Merged 22 (event-related) and 28 (README-related).
Added auto-register feature.
Added `on_slash_command`, `on_slash_command_error` events.
Added `get_all_commands` coroutine to `utils.manage_commands`.
Fixed type 2 and 5 not working at `SlashContext.send()` coroutine.
Fixed `guild_ids` and `has_subcommands` can be falsely overriden.
Changed `SlashContext.guild` is ID when cannot get guild from cache.
Changed some args of `send` and `edit` is keyword-only args.

Fixed subcommand raises KeyError at specific condition.

Fixed 16
Merged 18
Fixed some variables of model.SlashContext is missing when intents are not all enabled.
Added rate limit control.
Added subcommand support.

Added discord.Client support and did some bug fixes.
Supports cog from this version.
At next release, parameter `guild_id` at slash decorator will be deprecated since it is replaced by `guild_ids`.