[e2e] Enlist requirements to cover with tests

[mikementor]

Is your proposal related to a problem?

Currently there's no entry point for requirements <--~--> tests

Describe the solution you'd like

We should fix requirements in documentation, that also will help us with identifying coverage, current/needed

Describe alternatives you've considered

(Write your answer here.)

Additional context

(Write your answer here.)

[mikementor]

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1. Brokers
   1. topics
      1. add a topic
      2. clear messages of the topic
      3. remove topic
         1. [cases]
            1. button shouldn't be enabled/visible in read-only mode
      4. search for topic
      5. go to the topic settings
         1. [clear all messages]
         2. [delete topic]
         3. [edit settings]
         4. [tab:overview]
         5. [tab:messages]
            1. search for messages
         6. [tab:consumers]
         7. [tab:settings]
      6. toggle visibility of internal topics
         1. [cases]
            1. toggling should affect pagination
      7. pagination
         1. move to next page
         2. move to previous page
         3. [cases]
            1. buttons should disabled, when
2. [Topics]
3. [Consumers]
4. [Schema Registry]
5. [Kafka Connect]

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