fix(core): ensure propagation and change-tracking when useDefineForClassFields enabled

[B4nan]

Propagation on new entities you create via constructor are supported too, by modifying the entity class prototype, but this technique fails when useDefineForClassFields TypeScript compiler flag is enabled (which is true when targeting ES2022 or higher). You can get around this by using declare keyword in your entity definition, or by creating entity instances via em.create(), which will ensure the propagation is enabled.

Related #4216

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.01 ⚠️

Comparison is base (75dc4ed) 99.46% compared to head (785a67c) 99.45%.

Additional details and impacted files

@@            Coverage Diff             @@
##               v6    #4434      +/-   ##
==========================================
- Coverage   99.46%   99.45%   -0.01%     
==========================================
  Files         218      218              
  Lines       14797    14934     +137     
  Branches     3416     3423       +7     
==========================================
+ Hits        14718    14853     +135     
- Misses         77       79       +2     
  Partials        2        2              

Impacted Files	Coverage Δ
packages/core/src/utils/Configuration.ts	99.27% <ø> (+0.02%)	⬆️
packages/core/src/utils/ConfigurationLoader.ts	100.00% <ø> (ø)
packages/knex/src/AbstractSqlConnection.ts	100.00% <ø> (ø)
packages/core/src/entity/ArrayCollection.ts	100.00% <100.00%> (ø)
packages/core/src/entity/EntityFactory.ts	100.00% <100.00%> (ø)
packages/core/src/entity/EntityHelper.ts	98.62% <100.00%> (-1.38%)	⬇️
packages/core/src/entity/WrappedEntity.ts	100.00% <100.00%> (ø)
packages/core/src/typings.ts	100.00% <100.00%> (ø)
packages/core/src/unit-of-work/UnitOfWork.ts	99.65% <100.00%> (+<0.01%)	⬆️
packages/knex/src/AbstractSqlDriver.ts	99.82% <100.00%> (+<0.01%)	⬆️
... and 1 more

... and 33 files with indirect coverage changes

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