Add default project to organization default settings

[ctrombley]

Description

In atlas, we can now update the default project hence we need to add default project id to the organization default settings.

Note:

• I have added default project to the importer as well, is this a needed change?
• Cleaning up resources for a default project is a little tricky because default project cannot be deleted so, while testing I needed to set the default project to be the original default project to be able to delete the resource.

Remember to:

• Update the Change Log
• Update the Documentation

External links

Include any links here that might be helpful for people reviewing your PR. If there are none, feel free to delete this section.

• go-tfe documentation
• API documentation
• Jira

Output from Documentation Preview

Output from acceptance tests

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[netramali]

@ctrombley After thinking about it again, if !stateData.DefaultProjectID.IsNull() and planData.DefaultProjectID.IsNull() --> basically if the user didn't provide default project id but it already exists, we shouldn't remove it.

An approach we can take is to make the default project id required field. What do you think about that?

The other option is that we only ever do this options.DefaultProject = jsonapi.NewNullNullableRelationship[*tfe.Project]() when the plan has an explicit null set for the default project id