Additional changes:
* align vpc-connector interface to Cloud Functions
* split managed and unmanaged resources into separate files, this makes
easier to introduce further changes
* add support for contexts
* move `vpc_connector` variable to variables.tf for Cloud Functions
* remove `create` from `vpc_connector` in Cloud Functions as it was
sharing the meaning with `vpc_connector_create`
* exposing the network_id from the net-vpc module for use with tag bindings
* convert vpc_create to vpc_reuse
* Changed the reuse vars to standardised attributes
* fixed readme tests and schemas
* modified apigee blueprint to use vpc_reuse with network_id passthrough
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Co-authored-by: Ludovico Magnocavallo <ludomagno@google.com>
