Tag manager processor to add and remove tags manually

[graytaylor0]

Is your feature request related to a problem? Please describe.
As a user of data prepper and tags within data prepper, I would like to explicitly add or remove tags from Events with conditional expressions

Describe the solution you'd like
A tag_manager processor that can explicitly add or remove tags with conditions

processor:
  - tag_manager:
       add_tags: [ "tag_one", "tag_two" ]
       add_when: "/key == null"
       remove_tags: [ "tag_three", "tag_four" ]
       remove_when: "/key == null"

Describe alternatives you've considered (Optional)
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Originally mentioned in #629

[dlvenable]

Could we name this simply tag, or tags?

processor:
  - tag:
       add_tags: [ "tag_one", "tag_two" ]

or

processor:
  - tags:
       add_tags: [ "tag_one", "tag_two" ]