Resolve dead links in type docs.

[thantos]

Typedocs warns about dead links due to missing imports and the use of @link. Resolve these.

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warning Failed to resolve {@link Error} in Integration.__type with declaration references. This link will break in v0.24.
warning Failed to resolve {@link Authorizer} in MethodProps.authorizationType with declaration references. This link will break in v0.24.
warning Failed to resolve {@link Authorizer#token()} in MethodProps.authorizationType with declaration references. This link will break in v0.24.
warning Failed to resolve {@link expr} in APIGatewayVTL.exprToJson with declaration references. This link will break in v0.24.
warning Failed to resolve {@link expr} in APIGatewayVTL.qr with declaration references. This link will break in v0.24.
....