Crud: [feature request] add 'json_contain' operator

[Darkein]

I know we can override typeorm-operator.service.ts thanks to @Diluka , but it would be nice to add json_contain operator out of the box. What do you think ?

[Diluka]

@zMotivat0r made an operator validator to check operators and json_contains does not support all the databases. you can override in instead. it is reasonable.

[zMotivat0r]

@Darkein @Diluka I'll add custom operators this week

[Darkein]

@zMotivat0r it will be perfect, thanks 👍