feat(sequelize): dialectModule option

[sushantdhiman]

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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?
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Description of change

Added support for new configuration option dialectModule. Sequelize instance will use that dialect library instance rather than requiring default dialect module

Fixes #9608
Fixes #7354
Closes #9609

[codecov]

Codecov Report

Merging #9972 into master will increase coverage by 0.14%.
The diff coverage is 89.47%.

@@            Coverage Diff             @@
##           master    #9972      +/-   ##
==========================================
+ Coverage   96.24%   96.39%   +0.14%     
==========================================
  Files          63       63              
  Lines        9408     9395      -13     
==========================================
+ Hits         9055     9056       +1     
+ Misses        353      339      -14

Impacted Files	Coverage Δ
lib/sequelize.js	96.58% <ø> (ø)	⬆️
lib/dialects/mssql/connection-manager.js	88.6% <100%> (+3.9%)	⬆️
lib/dialects/postgres/connection-manager.js	93.51% <100%> (+3.08%)	⬆️
lib/dialects/mysql/connection-manager.js	95.23% <100%> (+5.38%)	⬆️
lib/dialects/sqlite/connection-manager.js	97.77% <100%> (+7.77%)	⬆️
lib/dialects/abstract/connection-manager.js	87.6% <81.81%> (-0.58%)	⬇️

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