[Notification]: Refactor component not to strict what content is contained, remove empty spaces from body text content

[xanxan]

Jira ticket: https://funidata.atlassian.net/browse/DS-297

Breaking changes:

• removed following inputs: link, externalLink, linkTitle
• removed inner BodyText component

Migration Guidelines:

• Application is responsible for all the content that is nested
  • so if you previously used removed Link inputs, just add a Link component inside Notification
  • If you had only text content, now it is recommended to wrap your inner text content with BodyText component

Notification Component doesn't strict what content is contained or interfere the content styling.
Also fixed body text not to include any empty space around the content text.
Updated notification documentation and tests.