chore(coderabbitai): Codify and improve config (#810)

Except what was already here, I changed next settings:

* Disable: related_issues, related_prs - to not make useless cross-links between PRs and issues
* Collapse Walkthrough - as it took too much place in PR and needed just for first interaction.
* Move summary to Walkthrough

---------

Co-authored-by: George L. Yermulnik <[email protected]>

Author: MaxymVlasov

.coderabbit.yaml

@@ -0,0 +1,19 @@
+# yaml-language-server: $schema=https://coderabbit.ai/integrations/schema.v2.json
+reviews:
+  # Collapse main AI comment by default, as it takes too much space when
+  # expanded. It also is needless for subsequent rounds of PR review, mostly
+  # only for the first one
+  collapse_walkthrough: true
+  # Move AI-generated summary from PR description to main AI comment. It
+  # hallucinates sometimes, especially with PRs that change code linting rules
+  high_level_summary_in_walkthrough: true
+  # Disable false-positive cross links to issues
+  related_issues: false
+  # Disable false-positive cross links to PRs
+  related_prs: false
+  # Disable useless Poem generation
+  poem: false
+
+  auto_review:
+    # Enable AI review for Draft PRs
+    drafts: true