Refactor input

[kmvanbrunt]

Moved logic specific to the main command line from Cmd.read_input() to Cmd._read_command_line().

No longer setting Cmd.session.input to a pipe since that causes warnings from prompt-toolkit.
For non-interactive sessions (self.stdin is a pipe), we use self.stdin.readline().

[github-actions]

🤖 Hi @kmvanbrunt, I've received your request, and I'm working on it now! You can track my progress in the logs for more details.

[codecov]

Codecov Report

❌ Patch coverage is 96.77419% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 99.19%. Comparing base (4f545de) to head (c488828).

Files with missing lines	Patch %	Lines
cmd2/cmd2.py	96.61%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1585      +/-   ##
==========================================
- Coverage   99.42%   99.19%   -0.23%     
==========================================
  Files          21       20       -1     
  Lines        4676     4613      -63     
==========================================
- Hits         4649     4576      -73     
- Misses         27       37      +10     

Flag	Coverage Δ
unittests	99.19% <96.77%> (-0.23%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[github-actions]

🤖 I'm sorry @kmvanbrunt, but I was unable to process your request. Please see the logs for more details.