tui: use RFC3339-alike format with second precision for "Time"

[aktau]

The current time format (Jan 2, 2006 at 3:04pm (MST)) has a few issues:

• It displays time at minute granularity, while profiles usually have have second-level (and more¹) granularity.
• It uses a 12-hour clock, which is tricky to handle at AM/PM switchovers, for people (like myself) who are not used to it. By contrast, a 24-hour clock is unambiguous.
• Minor: using names for months makes it more difficult to calculate with time differences.

Hence, I propose replacing it with an RFC3339-alike format, with spaces between elements for better readability.

Footnotes

1. https://github.com/golang/go/blob/3aa71c12eacd68ec16e7172d92aa5c6af32f0c3b/src/runtime/pprof/proto.go#L351 ↩

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.95%. Comparing base (0ed6a68) to head (6be65a6).
Report is 46 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #903      +/-   ##
==========================================
+ Coverage   66.86%   66.95%   +0.09%     
==========================================
  Files          44       44              
  Lines        9824     9857      +33     
==========================================
+ Hits         6569     6600      +31     
- Misses       2794     2817      +23     
+ Partials      461      440      -21     

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[aalexand]

@aktau It's unfortunate that no test had to be updated. Should we look into adding a test that would verify the change? My worry is that by just looking at the code I can't tell if we used a format string that will work as expected. If adding an automated test is too much hassle then could you confirm that you tested the change manually / locally?

[aktau]

OK, I added a test. PTAL.