SchemaFactory trigger an error when a schema doesn't have the @Schema decorator

[DanielSuhett]

PR Checklist

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

#1697

Issue Number: 1697

What is the new behavior?

When you call SchemaFactory.createForClass without a @Schema throw a new error.
Tests to check update with Schema.
Not extends anymore the mongoose Document because he overwrite the @Schema decorator

Does this PR introduce a breaking change?

• Yes
• No

extends mongoose Document trigger throw an error because the @Schema decorator don't run with it.

Other information