docs(hooks): add documentation for connection hooks

[schmod]

Pull Request check-list

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• Does npm run test or npm run test-DIALECT pass with this change (including linting)?
• Does the description below contain a link to an existing issue (Closes #[issue]) or a description of the issue you are solving?
• Have you added new tests to prevent regressions?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
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Description of change

Adds documentation for the beforeConnect() and afterConnect() hooks, API documentation for providing global hook definitions when constructing a Sequelize instance, and the corresponding TypeScript types.

Additionally, this corrects the TypeScript types to make operatorsAliases an optional configuration property (which was discovered when writing tests for the new types).

[codecov]

Codecov Report

Merging #10410 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #10410   +/-   ##
=======================================
  Coverage    96.3%    96.3%           
=======================================
  Files          92       92           
  Lines        9813     9813           
=======================================
  Hits         9450     9450           
  Misses        363      363

Impacted Files	Coverage Δ
lib/sequelize.js	96.35% <ø> (ø)	⬆️

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