Backpressure handling

[sl0thentr0py]

closes #2063

[codecov]

Codecov Report

Merging #2185 (7a3b48c) into master (0874ca8) will increase coverage by 5.45%.
The diff coverage is 98.46%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2185      +/-   ##
==========================================
+ Coverage   91.90%   97.36%   +5.45%     
==========================================
  Files          81      101      +20     
  Lines        3238     3792     +554     
==========================================
+ Hits         2976     3692     +716     
+ Misses        262      100     -162     

Components	Coverage Δ
sentry-ruby	98.06% <98.46%> (+0.07%)	⬆️
sentry-rails	94.98% <ø> (+49.22%)	⬆️
sentry-sidekiq	94.53% <ø> (∅)
sentry-resque	92.06% <ø> (ø)
sentry-delayed_job	94.44% <ø> (ø)
sentry-opentelemetry	100.00% <ø> (∅)

Files	Coverage Δ
sentry-ruby/lib/sentry-ruby.rb	96.42% <100.00%> (+0.57%)	⬆️
sentry-ruby/lib/sentry/background_worker.rb	100.00% <100.00%> (ø)
sentry-ruby/lib/sentry/configuration.rb	98.76% <100.00%> (+0.01%)	⬆️
sentry-ruby/lib/sentry/transaction.rb	100.00% <100.00%> (ø)
sentry-ruby/lib/sentry/transport.rb	99.03% <100.00%> (+0.01%)	⬆️
sentry-ruby/lib/sentry/backpressure_monitor.rb	97.72% <97.72%> (ø)

... and 33 files with indirect coverage changes

[st0012]

(I know it's not fully ready for review yet, but overall looks good to me 👍)