Feature: v3 notification features backport

[amadeo-alex]

This PR backports features that were developed as part of "v3 rewrite" project.
The added features were based on the Home Assistant's Android notifications documentation - https://companion.home-assistant.io/docs/notifications/notifications-basic/

Example 1: notification with 3 buttons, one input and tag & group so it can be cleared

service: notify.amadeo_pc
data:
  title: Fancy title
  message: Test message
  data:
    image: >-
      https://smea.uw.edu/wp-content/uploads/sites/11/2017/03/CURRENTSBLOG_Cat_2.jpg
    actions:
      - action: "yes"
        title: "Yes"
      - action: "no"
        title: "No"
      - action: "openuri"
        title: "Open URI"
        uri: "https://www.cat-lovers-only.com"
    inputs:
      - id: testId
        text: testText
        title: testTitle
    clickAction: "https://www.home-assistant.io/"
    tag: "dogsAreCoolToo"
    group: "cuddlyOnesTho"

Example 2: clear notification from "Example 1"

service: notify.amadeo_pc
data:
  message: clear_notification
  data:
    tag: "dogsAreCoolToo"
    group: "cuddlyOnesTho"

Example 3a: sticky notification (always requires a button so if there is no defined, a one called "Dismiss" will be automatically added)

service: notify.amadeo_pc
data:
  title: "I'm sticky"
  message: Gonna stay here I think
  data:
    sticky: true

Example 3b: sticky notification

service: notify.amadeo_pc
data:
  title: "I'm sticky"
  message: Gonna stay here I think
  data:
    actions:
      - action: "ok"
        title: "Ok"
    sticky: true

Example 4: "important notification" (overrides "sticky")

service: notify.amadeo_pc
data:
  title: "Don't miss me"
  message: "You're out of tea!"
  data:
    actions:
      - action: "buy"
        title: "Buy more"
      - action: "waterbros"
        title: "Water this time"
    importance: high