Introduce API Token Ephemeral Resource

[chrismarget-j]

This PR introduces our first Ephemeral Resource: apstra_api_token

Broad changes

• I had to upgrade Terraform CLI on my workstation in order to render the docs. Terraform prior to 1.10.0 doesn't know about Ephemeral Resources.
• The github.com/hashicorp/terraform-plugin-docs dependency also needed to be upgraded to generate docs for Ephemeral Resources.
• The minimum version of go needed to be updated in go.mod, I think because of tfplugindocs.
• The provider object, provider data, configure interfaces and documentation templates were extended to support ephemeral resources.

The new Ephemeral Resource:

apstra_api_token implements the following framework interfaces:

• ephemeral.EphemeralResource
• ephemeral.EphemeralResourceWithClose
• ephemeral.EphemeralResourceWithConfigure
• ephemeral.EphemeralResourceWithRenew

In Configure(), we extract the apstra.Client from provider data (no surprises here).

In Open(), we create a client based on the one passed in by the provider, log it in, extract the required token info, and set the Renew() time for shortly before the token expires.

In Renew(), we can't actually freshen the token. Renew() is a feature designed for "leased" credentials where the lease can be renewed without replacing the value. All we can do is raise warnings or errors. If the credential is not yet expired, we raise a warning and update the renew time. If it's expired, we raise an error.

In Close(), we call the logout API unless the user asked us not to or the token is already expired.

Odds and Ends

Bugfixes in github.com/hashicorp/terraform-plugin-docs cause several documentation pages to render differently even though the source data didn't change.

[chrismarget-j]

Closes #992