unified sender tag

[fedekunze]

Closes #3775

cc: @faboweb @jbibla

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added a relevant changelog entry: sdkch add [section] [stanza] [message]

• rereviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #4057 into develop will decrease coverage by 0.02%.
The diff coverage is 92.85%.

@@             Coverage Diff             @@
##           develop    #4057      +/-   ##
===========================================
- Coverage    59.98%   59.96%   -0.03%     
===========================================
  Files          212      212              
  Lines        15123    15124       +1     
===========================================
- Hits          9072     9069       -3     
- Misses        5431     5435       +4     
  Partials       620      620