ref(slack): track response_urls in send_slack_response

[cathteng]

Small refactor for the send_slack_response. Also adds back the response_url when initializing the params as IdentityParams, so we can properly log the kinds of response_urls we're getting.

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 77.98%. Comparing base (20a5209) to head (61b1f26).
Report is 8 commits behind head on master.

❗ Current head 61b1f26 differs from pull request most recent head 79d6289

Please upload reports for the commit 79d6289 to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #73087      +/-   ##
==========================================
- Coverage   77.98%   77.98%   -0.01%     
==========================================
  Files        6619     6621       +2     
  Lines      295439   295480      +41     
  Branches    50890    50892       +2     
==========================================
+ Hits       230393   230416      +23     
- Misses      58771    58793      +22     
+ Partials     6275     6271       -4     

Files	Coverage Δ
...c/sentry/integrations/slack/views/link_identity.py	69.33% <100.00%> (-8.00%)	⬇️
...sentry/integrations/slack/views/unlink_identity.py	77.61% <100.00%> (-4.48%)	⬇️
...s/integrations/slack/link_slack_user_identities.py	86.95% <100.00%> (+0.28%)	⬆️
...c/sentry/integrations/slack/utils/notifications.py	79.12% <42.85%> (-8.66%)	⬇️

... and 10 files with indirect coverage changes