actions: create automatic controller db updating workflow

.github/workflows/scripts/controller-db/.gitignore

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+*.txt

.github/workflows/scripts/controller-db/update-db.py

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+import os
+
+relevant_categories = [
+  "# Mac OS X",
+  "# Linux"
+]
+
+header_lines = []
+new_db_contents = []
+
+def is_relevant_category(line):
+  for category in relevant_categories:
+    if category in line:
+      return True
+  return False
+
+with open("./game_controller_db.txt") as file:
+  lines = file.readlines()
+  finished_header = False
+  processing_section = False
+  for line in lines:
+    if finished_header is False:
+      header_lines.append(line)
+      if line == "\n":
+        finished_header = True
+    if processing_section and line == "\n":
+      processing_section = False
+      new_db_contents.append("\n")
+    if is_relevant_category(line) and processing_section is False:
+      processing_section = True
+      new_db_contents.append(line)
+    elif processing_section:
+      new_db_contents.append(line)
+
+os.remove("./game_controller_db.txt")
+with open("./game_controller_db.txt", "w") as f:
+  f.writelines(header_lines)
+  f.writelines(new_db_contents)

.github/workflows/update-controller-db.yml

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+name: 🏭 Update Controller Database
+
+on:
+  schedule:
+    - cron: "0 16 * * 1" # every monday @ 12pm EST - https://crontab.guru/#0_16_*_*_1
+
+jobs:
+  update-controller-db:
+    if: github.repository == 'PCSX2/pcsx2'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Get Latest DB and Prepare DB File
+        run: |
+          cd .github/workflows/scripts/controller-db/
+          wget -O game_controller_db.txt https://raw.githubusercontent.com/gabomdq/SDL_GameControllerDB/master/gamecontrollerdb.txt
+          python ./update-db.py
+          mv ./game_controller_db.txt ${{github.workspace}}/pcsx2/PAD/Linux/res/game_controller_db.txt
+
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v3
+        with:
+          title: "pad-linux: Update to latest controller database"
+          commit-message: "pad-linux: Update to latest controller database."
+          committer: "PCSX2 Bot <PCSX2Bot@users.noreply.github.com>"
+          author: "PCSX2 Bot <PCSX2Bot@users.noreply.github.com>"
+          body: "Weekly automatic update of SDL Controller DB for Linux / Mac OS"
+          reviewers: lightningterror