fix: use isArray util function to check the type of the array

[kiaking]

When checking a value is a type of array, using foo instanceof Array was causing false negative in Nuxt server side env. It's fixed by using Array.isArray() instead.

This PR adds isArray utility function, and replaces all Array.isArray() and foo instanceof Array condition checks.

Type of PR:

• Bugfix
• Feature
• Enhancement
• Documentation
• Other

Breaking changes:

• No
• Yes

[codecov]

Codecov Report

Merging #596 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #596   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          47     47           
  Lines        1904   1910    +6     
  Branches      270    270           
=====================================
+ Hits         1904   1910    +6

Impacted Files	Coverage Δ
src/attributes/relations/Relation.ts	100% <100%> (ø)	⬆️
src/attributes/relations/MorphedByMany.ts	100% <100%> (ø)	⬆️
src/modules/Actions.ts	100% <100%> (ø)	⬆️
src/schema/IdAttribute.ts	100% <100%> (ø)	⬆️
src/attributes/relations/BelongsToMany.ts	100% <100%> (ø)	⬆️
src/query/loaders/Loader.ts	100% <100%> (ø)	⬆️
src/attributes/relations/MorphToMany.ts	100% <100%> (ø)	⬆️
src/query/processors/Normalizer.ts	100% <100%> (ø)	⬆️
src/query/rollcallers/Rollcaller.ts	100% <100%> (ø)	⬆️
src/query/filters/WhereFilter.ts	100% <100%> (ø)	⬆️
... and 3 more

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