Motion to Vacate | Create "De Novo" appeal stream

[nanotone]

Description / Acceptance criteria

When a judge grants a Motion to Vacate with disposition "Vacate and de novo",

• Create a new De Novo appeal stream with these attributes (see tech notes):
  • stream type De Novo
  • docket number same as that of the original appeal
• Create the request issues contesting the vacated decision issues (see tech notes)
• Create initial tasks for the newly-created appeal (see tech notes)

Background/context

Appeal streams can currently have one of three stream types: Original, Vacate, and De Novo. When a judge grants an MTV with disposition "vacate and de novo", both a Vacate-type appeal and a De Novo-type appeal are created, resulting in a total of three appeal streams sharing the same docket number.

Technical notes

Each Appeal's stream type is currently stored in its stream_type database field, and accessed either via either the corresponding #stream_type method or just #type (for data-processing compatibility). The DB field is subject to an ActiveRecord enum restriction, and De Novo is already one of the allowed values.

When creating a new Appeal with parameters different from the default (stream type: Original), it is important to specify both the non-default type (De Novo) and docket number (identical to that of the original appeal). Otherwise, the logic to generate a new docket number from the receipt date and ID will kick in. It may be worthwhile to write a new method -- perhaps on the Appeal model, to be called on the original appeal -- to encapsulate this behavior and prevent data errors.

This creation can be done as part of outcoding (see BvaDispatchTask#outcode). See also #13222 for similar work on creating the Vacate appeal stream when going down any one of the three Grant lanes.

See create_stream and create_new_stream_tasks in https://github.com/department-of-veterans-affairs/caseflow/pull/13325/files for creating the new appeal stream and initial tasks

See create_contesting_request_issue! in https://github.com/department-of-veterans-affairs/caseflow/pull/13173/files for creating request issues