feat: Improve config builders

[sfc-gh-asawicki]

Improve how we build config models:

• explore HCL v1 lib
• generate provider config builder
• generate datasource config builder
• generate config using hcl v1 lib
• support objects, lists, and sets
• use provider config in provider setup tests
• use datasource generated config in one test for databases datasource
• use support for objects and lists in one view resource acceptance test
• extract nullVariable to own file
• cleanup in bettertestspoc/config directory
• add all datasources to provider/datasources
• deprecate old config builder and config variables from config methods - undeprecated for now because of linter (and I could not quickly find how to disable it; will do in a follow-up)

References:

• https://developer.hashicorp.com/terraform/language/syntax/json
• https://github.com/hashicorp/hcl/blob/56a9aee5207dbaed7f061cd926b96fc159d26ea0/json/spec.md

TODOs (next PRs - soon):

• rename package model to resourcemodel
• add generating MarshalJSON() function
• migrate resources to new config generation method (above needed first)
• improve unquoteDependsOnReferences method

TODOs (next PRs - later, left as next steps in readme):

• add config builders for other block types (Variable, Output, Localsl, Module, Terraform)
• add provider to resource/datasource models (use in the grant_ownership_acceptance_test)
• explore HCL v2 in more detail (especially struct tags generation; probably with migration to plugin framework because of schema models)
• introduce some common interface for all three existing models (ResourceModel, DatasourceModel, and ProviderModel)
• rename ResourceSchemaDetails (because it is used for the datasources and provider too)
• consider duplicating the builders template from resource (currently same template used for datasources and provider)
• consider merging ResourceModel with DatasourceModel (currently the implementation is really similar)

[github-actions]

Integration tests failure for 840b92891397cd45eb33354465382f5433b00e79

[github-actions]

Integration tests failure for 669caa19edfd70b33c6a05ed012821cd311c430e