WIP: add configurable detach delay to logs

[laurazard]

- What I did

Hacky PR for demonstration/discussion purposes only.

Addresses: #5305

- How I did it

- How to verify it

• docker run -d --name bork alpine sh -c "while true; do echo hi; sleep 1; done"
• docker logs -f --delay 3 bork
• (in another terminal) docker restart bork

- Description for the changelog

- A picture of a cute animal (not mandatory but encouraged)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 29.62963% with 19 lines in your changes missing coverage. Please review.

Project coverage is 61.41%. Comparing base (826fc32) to head (f632123).
Report is 10 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5307      +/-   ##
==========================================
- Coverage   61.45%   61.41%   -0.05%     
==========================================
  Files         299      299              
  Lines       20856    20882      +26     
==========================================
+ Hits        12818    12824       +6     
- Misses       7122     7142      +20     
  Partials      916      916              

[vvoland]

We could do what tail does and put this behind a separate -F option:

     -f      The -f option causes tail to not stop when end of file is reached, but rather to wait for additional data to be ap‐
             pended to the input.  The -f option is ignored if the standard input is a pipe, but not if it is a FIFO.

     -F      The -F option implies the -f option, but tail will also check to see if the file being followed has been renamed or
             rotated.  The file is closed and reopened when tail detects that the filename being read from has a new inode number.

             If the file being followed does not (yet) exist or if it is removed, tail will keep looking and will display the file
             from the beginning if and when it is created.

             The -F option is the same as the -f option if reading from standard input rather than a file.

So basically:

• -f would only work on existing containers and exit when the container ends
• -F would never exit, it would always just wait for the container, even if it doesn't exist at the time

[laurazard]

Ooh, I like that UX.