Allow negative chat ID for Telegram

[olafz]

Description:

The latest version of HASS requires a positive integer for CHAT_ID in Telegram:

Invalid config for [notify.telegram]: value must be at least 0 for dictionary
value @ data['chat_id']. Got '-12345678'. (See ?, line ?). Please check the
docs at https://home-assistant.io/components/notify.telegram/

However, this breaks group chats within Telegram: if the chat is a group, the chat id is negative. If it is a single person, the chat id is positive. This PR allows for group chats again.

[mention-bot]

@olafz, thanks for your PR! By analyzing the history of the files in this pull request, we identified @azogue, @sander76 and @fabaff to be potential reviewers.

[homeassistant]

Hi @olafz,

It seems you haven't yet signed a CLA. Please do so here.

Once you do that we will be able to review and accept this pull request.

Thanks!

[azogue]

You missed another in line 87:

BASE_SERVICE_SCHEMA = vol.Schema({
    vol.Optional(ATTR_TARGET): vol.All(cv.ensure_list, [cv.positive_int]),

I didn't know about the negative chat_ids for groups...

Apart from that, you will have to make some changes to allow communication with groups:

• When getting the message data (in the _get_message_data method), where the user_id is added, the chat_id should also be added, in order to be able to respond to the group instead of the user. And change the condition to something like ('text' not in msg_data and 'data' not in msg_data and 'chat' not in msg_data).
• In process_message, when receiving a new_chat_participant message, there will be an unhandled KeyError when trying to get the non-existent 'text' field.

[olafz]

Superseded by #7689 apparently?