Added \echo & \qecho for Issue #1335

[ERYoung11]

Description

I added a simple \echo & \qecho command. \echo always prints to STDOUT per the documentation. \qecho prints to the current query output stream per the documentation

Checklist

• I've added this contribution to the changelog.rst.
• I've added my name to the AUTHORS file (or it's already there).

• I installed pre-commit hooks (pip install pre-commit && pre-commit install), and ran black on my code.
• Please squash merge this pull request (uncheck if you'd like us to merge as multiple commits)

[codecov-commenter]

Codecov Report

Patch coverage: 51.91% and project coverage change: -4.62 ⚠️

Comparison is base (6884c29) 84.15% compared to head (01e29d5) 79.53%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1371      +/-   ##
==========================================
- Coverage   84.15%   79.53%   -4.62%     
==========================================
  Files          21       25       +4     
  Lines        2720     2986     +266     
==========================================
+ Hits         2289     2375      +86     
- Misses        431      611     +180     

Impacted Files	Coverage Δ
pgcli/completion_refresher.py	91.76% <ø> (+1.17%)	⬆️
pgcli/magic.py	0.00% <0.00%> (ø)
pgcli/packages/parseutils/tables.py	97.67% <ø> (ø)
pgcli/packages/sqlcompletion.py	97.67% <ø> (ø)
pgcli/pgcompleter.py	96.95% <ø> (ø)
pgcli/pgstyle.py	64.00% <ø> (ø)
pgcli/pgtoolbar.py	31.57% <0.00%> (+0.15%)	⬆️
pgcli/pyev.py	15.38% <15.38%> (ø)
pgcli/explain_output_formatter.py	46.15% <46.15%> (ø)
pgcli/key_bindings.py	52.94% <66.66%> (-0.19%)	⬇️
... and 8 more

... and 1 file with indirect coverage changes

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[ERYoung11]

@j-bennet @amjith Any issues with this PR that I can address? (besides that changelog.rst now has a conflict)

[j-bennet]

LGTM.

[ERYoung11]

@j-bennet @amjith This PR is ready. Sorry for the delay!

[j-bennet]

@ERYoung11 The PR is fine, but why not add the command to pgspecial?

[ERYoung11]

@j-bennet Great point! I'll rework it and resubmit.

[j-bennet]

So, pgspecial didn't happen :), but I merged the PR. It's a nice feature. Thank you @ERYoung11 !