Accelerate block tag iteration

[peterallenwebb]

resolves dbt-labs/dbt-core#9037

Description

The process of finding and iterating through jinja blocks could be quite slow. These changes accelerate the process by caching useful information about what searches have already been performed.

Many thanks to @fredriv for pointing out that this was still a problem and pushing for a fix.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have signed the CLA
• I have run this code in development and it appears to resolve the stated issue
• I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR
• I have run changie new to create a changelog entry

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the contributing guide.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.48%. Comparing base (ed11c6c) to head (6b18e61).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #205      +/-   ##
==========================================
+ Coverage   68.33%   68.48%   +0.14%     
==========================================
  Files          52       52              
  Lines        3373     3389      +16     
==========================================
+ Hits         2305     2321      +16     
  Misses       1068     1068              

Flag	Coverage Δ
unit	68.48% <100.00%> (+0.14%)	⬆️

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