Feature: Use dbt-core starter project as baseline for split projects

[nicholasyager]

Description and motivation

A common question for users of dbt-meshify is "why does the split project look ... odd?" In most cases, this is a byproduct of the existing split command creating only necessary directories and files in the split project. While functional, this is not the ideal experience for users.

This PR updates our method for creating projects, to instead start by creating a new starter project in the target directory, add all directories and files of interest, and then update the starter dbt_project.yml file using the sub-project's configuration information. The benefits to this approach are:

1. Sub-projects have all the standard files and directories for a dbt project.
2. The sub-project have a familiar dbt_project.yml file experience.

Along the way, I also implemented the following:

1. Tests that confirm the presence of standard dbt directories in sub-projects on creation.
2. Added a new Change type (Directorychange), file manager (DirectoryManager) and directory editor (DirectoryEditor) for interacting with directory structures instead of files. Some minor refactoring was implemented along the way.

Resolves: #124
Resolves: #153

Example dbt_project.yml

# Name your project! Project names should contain only lowercase characters
# and underscores. A good package name should reflect your organization's
# name or the intended use of these models
name: 'customers'
version: '1.0.0'
config-version: 2

# This setting configures which "profile" dbt uses for this project.
profile: 'split_proj'

# These configurations specify where dbt should look for different types of files.
# The `model-paths` config, for example, states that models in this project can be
# found in the "models/" directory. You probably won't need to change these!
model-paths:
  - models
analysis-paths:
  - analyses
test-paths:
  - tests
seed-paths:
  - seeds
  - jaffle_data
macro-paths:
  - macros
snapshot-paths:
  - snapshots

clean-targets:         # directories to be removed by `dbt clean`
  - target
  - dbt_packages
models:
  customers:
    +on_schema_change: append_new_columns
    example:
      +materialized: view
require-dbt-version:
  - '>=1.7.0'
  - <1.8.0
seeds:
  +schema: jaffle_raw
vars:
  truncate_timespan_to: '{{ current_timestamp() }}'

Note the preserved comments and formatting in the bog-standard parts of the YAML file.

[dave-connors-3]

🦞

[dave-connors-3]

i remember this line being pretty /shrug at the time i wrote it -- any chance you tested removing this line and seeing if it worked? I feel like it may not in be in the yml from the starter project, and therefore not something we'd need to worry about anymore.

[nicholasyager]

Based on my tests, if we remove it from here, it will be rendered in the sub-project's dbt_project.yml. Is that the desired behavior?

[dave-connors-3]

no i wouldn't say so 😅 i think my thought was that it may no longer be in the YML we start with now that we're using the official starter project file. if it's still there, I'd vote not to render it