docs(new docs site): removes old sphinx doc site with gatsby (#10784)

* Remove old apache sphinx doc site with refreshed gatsby

* remove rando

* add licenses

* excluing .mdx files from license checks

* fixes

* Clean up sphinx references

* Addressed comments

* colors and tweaks

* more fixes

* add dummy docs/requirements.txt to satisfy stupid fossa

* cp .prettierrc

* more licenses

* minor touchups

* reqs

* removing old videos

* add github buttons

* prettier

* tweaks

* Eugenia/Fix some of the images and modified some of database pages

* add subheadernav

* add side headers nav and more responsive design for docs

* update resources page and other styling updates

* linting

* tweaks

* removing windows and align:center

* update resources

* remove links and and card hearder

* lots of styling tweaks

* Tweaks and minor improvements

* lint

* fix CI

* trigger pre-comimt

* rererefix CI

Co-authored-by: Maxime Beauchemin <maximebeauchemin@gmail.com>
Co-authored-by: Eugenia Moreno <eugenia@Eugenias-MBP.fios-router.home>
Co-authored-by: Evan Rusackas <evan@preset.io>

.github/workflows/superset-docs.yml

@@ -1,36 +0,0 @@
-# Python linting and docs
-name: Docs
-
-on: [push, pull_request]
-
-jobs:
-  lint:
-    runs-on: ubuntu-18.04
-    strategy:
-      matrix:
-        python-version: [3.7]
-    steps:
-    - name: Checkout code
-      uses: actions/checkout@v2
-    - name: Setup Python
-      uses: actions/setup-python@v2.1.1
-      with:
-        python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
-      uses: apache-superset/cached-dependencies@b90713b
-      with:
-        run: |
-          apt-get-install
-          pip-upgrade
-          pip install -r requirements/testing.txt
-          pip install -r requirements/documentation.txt
-
-    - name: pylint
-      # `-j 0` run Pylint in parallel
-      run: pylint -j 0 superset
-
-    - name: pre-commit
-      run: pre-commit run --all-files
-
-    - name: Build documentation
-      run: sphinx-build -b html docs _build/html -W