fix(functions): Update index-kit-migration.ts template (#11017)

* fix(functions): Update index-kit-migration.ts template to accomodate ext:export variables

* labels are defined as a string, splitting the key values pairs in a "key1:value,key2:value" format. Now they will be parsed and returned as a dict for the "labels" global option.
* If there is no vpc connector egress setting defined, ext:export will populate the value with "VPC_CONNECTOR_EGRESS_SETTINGS_UNSPECIFIED". Now we add a check for this case