Use config.Reference.TerraformName instead of config.Reference.Type

[ulucinar]

Description of your changes

This PR replaces usages of upjet's config.Reference.Type API with config.Reference.TerraformName. In crossplane/upjet#400, we are deprecating the config.Reference.Type API in favor of config.Reference.TerraformName. We had introduced config.Reference.TerraformName in crossplane/upjet#12 and it's a more stable and less error prone API compared to config.Reference.Type because it automatically accounts for the configuration changes affecting the cross-resource reference target's kind name, group or version. We've already been discouraging the config.Reference.Type in favor of config.Reference.TerraformName since it's been introduced.

This PR is a precursor for #733, in which we will start generating the v1beta2 APIs for certain resources (those with singleton lists in their Terraform schemas). When the config.Reference.Type is used to define the reference target, the API version can be omitted for the targets in the same group and version. In those cases, if the referencing resource has been generated at v1beta2 whereas the reference target lacks that version, the generated resolver is not valid. Using config.Reference.TerraformName instead will help us in future maintenance because it automatically accounts for generating the cross-resource reference resolvers in the generated version. This is also one of the reasons we are deprecating config.Reference.Type.

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

A successful uptest run is registered here for a resource affected by this change: https://github.com/crossplane-contrib/provider-upjet-azure/actions/runs/9037709362/

Also checked for any unexpected changes in the generated resolvers (apis/../zz_generated.resolvers.go files).

[ulucinar]

/test-examples="examples/network/subnet.yaml"

[ulucinar]

/test-examples="examples/network/subnet.yaml"

[sergenyalcin]

Thanks @ulucinar LGTM!