Add Sentry.with_exception_captured helper

[st0012]

This PR adds the Sentry.with_exception_captured helper to simplify exception rescuing/reporting logic:

Sentry.with_exception_captured do
 1/1 #=> 1 will be returned
end

Sentry.with_exception_captured do
 1/0 #=> ZeroDivisionError will be reported and re-raised
end

It's the same as:

begin
  my_code
rescue Exception => e
  Sentry.caputre_exception(e)
  raise
end

[codecov-commenter]

Codecov Report

Merging #1814 (2ea8d21) into master (daeb133) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1814      +/-   ##
==========================================
+ Coverage   98.45%   98.46%   +0.01%     
==========================================
  Files         145      145              
  Lines        8661     8675      +14     
==========================================
+ Hits         8527     8542      +15     
+ Misses        134      133       -1     

Impacted Files	Coverage Δ
sentry-ruby/lib/sentry-ruby.rb	96.29% <100.00%> (+0.09%)	⬆️
sentry-ruby/spec/sentry_spec.rb	99.77% <100.00%> (+<0.01%)	⬆️
sentry-ruby/lib/sentry/breadcrumb.rb	100.00% <0.00%> (+3.70%)	⬆️

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