Infer bigint data type

[Brobin]

This PR infers the data type of bigint to DataTypes.BIGINT. Previously, using just @Column on a bigint field produced this error:

Specified type of property 'id' cannot be automatically resolved to a sequelize data type. Please define the data type manually

This will lead to cleaner code as the dataType argument can be removed from @Column(DataType.BIGINT)

class Test extends Model {
  @PrimaryKey
  @AutoIncrement
-  @Column(DataType.BIGINT)
+  @Column
  id: bigint;
}

[codecov]

Codecov Report

Merging #893 (1219705) into master (6547ffd) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #893   +/-   ##
=======================================
  Coverage   95.20%   95.20%           
=======================================
  Files         117      117           
  Lines        1126     1127    +1     
  Branches      129      129           
=======================================
+ Hits         1072     1073    +1     
  Misses         22       22           
  Partials       32       32           

Impacted Files	Coverage Δ
src/sequelize/data-type/data-type-service.ts	84.61% <100.00%> (+1.28%)	⬆️

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[lukashroch]

@Brobin, awesome, can you please update the Type inference table in readme file?

[YSHIDM]

I need Json, what can I do