Dbt-table-diff

**Goal:**
Cleaner `README.md` with badges to highlight repo details

**Changes:**
- Update version in `setup.py` to `v2.2.1`
- Update version in `action.yml` to `2.2.1`
- Move relative imports of `dbt_table_diff/arg_parser.py` from `dbt_table_diff/run_sql_checks.py` to `dbt_table_diff/__init__.py`

Goal:
- Add [dbt_table_diff](https://pypi.org/project/dbt-table-diff/) as a `PyPi` package.

---

Use Cases:

1. **Code Example:**


from dbt_table_diff import run_dbt_table_diff

run_dbt_table_diff(
project_id="ultimate-bit-359101",
keyfile_path="secrets/bq_keyfile.json",
manifest_file="target/manifest.json",
dev_prefix="dev_",
prod_prefix="prod_",
fallback_prefix="fb_",
custom_checks_path="",
ignored_schemas=[],
irregular_schemas=[],
org_name="org-not-included",
repo_name="dbt_example",
pr_id="2",
auth_token="my_github_pat",
)


---

2. **CLI Example:**

python3 -m dbt_table_diff -t $GH_TOKEN -o org-not-included -r dbt_example -l 2 \
--manifest_file 'target/manifest.json' --project_id 'ultimate-bit-359101' \
--keyfile_path 'secrets/bq_keyfile.json' --dev_prefix 'dev_' --prod_prefix 'prod_' --fallback_prefix 'fb_'


---

3. **(Existing) [Github Action Example](https://github.com/org-not-included/dbt_example/pull/2)**

Enable `dbt_table_diff` to be leveraged as:
- Github Action
- CLI Command (PyPi)
- Import Python Package (PyPi)