[live] Restore sys.stderr when an exception happens during a refresh

[olivierphi]

Without this the user sees no error displayed in their terminal - and even capturing the exception and displayed their own error reporting is ineffective.

Type of changes

• Bug fix
• New feature
• Documentation / docstrings
• Tests
• Other

Checklist

• I've run the latest black with default args on new code.
• I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate.
• I've added tests for new code.
• I accept that @willmcgugan may be pedantic in the code review.

Description

fixes #2291

[codecov-commenter]

Codecov Report

Merging #2305 (cf99a8d) into master (14d47c9) will decrease coverage by 0.12%.
The diff coverage is 94.26%.

@@            Coverage Diff             @@
##           master    #2305      +/-   ##
==========================================
- Coverage   98.88%   98.76%   -0.13%     
==========================================
  Files          73       73              
  Lines        7629     7676      +47     
==========================================
+ Hits         7544     7581      +37     
- Misses         85       95      +10     

Flag	Coverage Δ
unittests	98.76% <94.26%> (-0.13%)	⬇️

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

Impacted Files	Coverage Δ
rich/_export_format.py	100.00% <ø> (ø)
rich/live.py	97.90% <40.00%> (-2.10%)	⬇️
rich/console.py	98.29% <96.03%> (-0.49%)	⬇️
rich/syntax.py	99.30% <100.00%> (+0.02%)	⬆️
rich/terminal_theme.py	100.00% <100.00%> (ø)
rich/traceback.py	98.68% <0.00%> (-0.88%)	⬇️

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[willmcgugan]

LGTM Will add a issue for the general case of refresh failing after start.