Add new Canvas built in functions to the deno-sdk

Summary

This PR add the new deno-sdk built in Slack functions for canvas

canvas create
channel canvas create
copy canvas
canvas update content
share canvas

Also adds new primitives types:

canvas id -> slack#/types/canvas_id id of the canvas
canvas_template_id -> slack#/types/canvas_template_id id of a canvas template
expanded_rich_text -> slack#/types/expanded_rich_text is similar to rich text but in the future will support extra types

Notes

Requirements

Manifest

In order to use the Canvas deno-sdk function its required to enable appHome and set messagesTabEnabled to true and messagesTabReadOnlyEnabled to false. This is required since Canvas Sharing require sending messages in order to Share and transfer ownership of canvases

 features: {
    appHome: {
      messagesTabEnabled: true,
      messagesTabReadOnlyEnabled: false,
    },
  },

Create Canvas

For creating a canvas a user will need to set the canvas_create_type to blank or template, it defaults to blank is if not passed. In case that template is set then the user will have to provide canvas_template_id, in which case the canvas will copy the template to the newly created standalone canvas

Create Channel Canvas

For creating a channels canvas a user will need to set the canvas_create_type to blank or template, it defaults to blank is if not passed. In case that template is set then the user will have to provide canvas_template_id, in which case the canvas will copy the template to the newly created channel canvas

Update Canvas Content

For updating the canvas content the canvas_update_type will determine if the user want to update a standalone canvas or a channel canvas, by default if is not set it will be treated as standalone. If the user set standalone then a canvas_id need to be provided, otherwise if the user set channel_canvas it will need to provide a channel_id of the channel canvas that the user want to update.

If the user set the section_id then the content will be updated to the top of bottom of the section, this is the section_id of the heading sections, otherwise if is not set the content will be updated to the top or bottom of the canvas

Testing

Create an app using the functions and see that it perform the actions

[x] I've read and understood the Contributing Guidelines and have done my best effort to follow them.
[x] I've read and agree to the Code of Conduct.
[x] I've ran deno task test after making the changes.

slackapi / deno-slack-sdk