Add human readable parameters for long topic retention periods

[henriksdal]

Is your feature request related to a problem? Please describe.
I have many topics with different retention policies in descriptor file like this:

context: 'context'
projects:
  - name: 'my-project'
    topics:
      - name: 'topic1'
        config:
          retention.ms: 604800000
          ...
      - name: 'topic2'
        config:
          retention.ms: 6048000000
          ...
        ...

Retentions may be in wide range (from several hours to months) and sometimes it's really hard to see difference between multiples like: 1 day (604800000 ms) and 10 days (6048000000 ms).
It would be nice to be able to use human readable parameters like retention.hours, retention.days in descriptor files.

Describe the solution you'd like
So, user will specify one of retention.{ms,hours,days} in descriptor file. If found specified keywords retention.hours or retention.days, it is needed to convert these keywords to appropriated retention.ms values while creating\updating topics. Something like log.retention.{ms,minutes,hours} properties for brokers, but for topics.