fix(types): specified this for getters and setters in fields

[knoid]

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?
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Description of change

Added typings for this on getters and setters in attribute definitions.

[codecov]

Codecov Report

Merging #11648 into master will increase coverage by 3.38%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #11648      +/-   ##
==========================================
+ Coverage   92.47%   95.86%   +3.38%     
==========================================
  Files          91       91              
  Lines        8903     8987      +84     
==========================================
+ Hits         8233     8615     +382     
+ Misses        670      372     -298

Impacted Files	Coverage Δ
lib/dialects/mariadb/query-generator.js	14.28% <0%> (-85.72%)	⬇️
lib/dialects/mariadb/data-types.js	50.98% <0%> (-49.02%)	⬇️
lib/dialects/mariadb/index.js
lib/dialects/mariadb/connection-manager.js
lib/dialects/mariadb/query.js
lib/dialects/sqlite/index.js	100% <0%> (ø)
lib/dialects/sqlite/query.js	98.65% <0%> (ø)
lib/dialects/sqlite/connection-manager.js	100% <0%> (ø)
lib/data-types.js	91.34% <0%> (+0.34%)	⬆️
lib/dialects/abstract/query-generator.js	97.01% <0%> (+0.51%)	⬆️
... and 8 more

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