[Feature] Add Svensson Nominal Yield Curve From Federal Reserve (#7338)

* add svensson yield curve, cleanup fomc documents endpoint, make provider a standalone extension, move apps from platform-api into extension, and update some models to add prefix/suffix in widget definitions

* black

* do what codeQL says

* black again

* use get_args instead of Literal.__args__

* linting

* test items

* grammar police

* test functions need to start with test_*

* test params

* add total factor productivity from sf fed

* openpyxl required for Excel file handling

* grammar police

* inflation expectations

* Update pr-description check action to properly handle quotes

---------

Co-authored-by: deeleeramone <>
Co-authored-by: Theodore Aptekarev <aptekarev@gmail.com>

.github/workflows/pr_description.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Check PR description
         shell: bash
         run: |
-          body="${{ github.event.pull_request.body }}"
+          body="$(jq -r .pull_request.body "$GITHUB_EVENT_PATH")"
           if [ -z "$(echo "$body" | tr -d '[:space:]')" ]; then
             echo "::error::PR description is empty. Please provide a description of the change."
             exit 1