ENH: Show info on credential setup in wtf()

[mih]

Would look something like this (paths truncated):

 % datalad wtf -S credentials
 # WTF
 ## credentials
   - keyring:
     - active_backends:
       - SecretService Keyring
       - PlaintextKeyring with no encyption v.1.0 at ...keyring_pass.cfg
     - config_file: ....config/python_keyring/keyringrc.cfg
     - data_root: ....local/share/python_keyring

If got tired of looking up the code snippets in the keyring docs to
run when switching machines, and discovering the left-overs of previous
configuration attempts.

Related to gh-4981

[codecov]

Codecov Report

Merging #4982 into master will increase coverage by 0.22%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #4982      +/-   ##
==========================================
+ Coverage   89.77%   89.99%   +0.22%     
==========================================
  Files         290      292       +2     
  Lines       40708    40995     +287     
==========================================
+ Hits        36546    36894     +348     
+ Misses       4162     4101      -61     

Impacted Files	Coverage Δ
datalad/plugin/wtf.py	83.53% <100.00%> (+2.44%)	⬆️
datalad/downloaders/tests/test_s3.py	51.94% <0.00%> (-20.15%)	⬇️
datalad/downloaders/s3.py	40.51% <0.00%> (-17.16%)	⬇️
datalad/distribution/create_sibling.py	85.02% <0.00%> (-0.57%)	⬇️
datalad/tests/utils.py	86.79% <0.00%> (-0.36%)	⬇️
datalad/config.py	96.65% <0.00%> (-0.16%)	⬇️
datalad/core/local/run.py	99.09% <0.00%> (-0.01%)	⬇️
datalad/support/github_.py	78.65% <0.00%> (ø)
datalad/downloaders/http.py	81.85% <0.00%> (ø)
datalad/core/local/create.py	94.44% <0.00%> (ø)
... and 41 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c33bd4e...b297e93. Read the comment docs.