Reorganize files, address review comments

Author: flodolo

.github/fluent_linter_config.yml .github/fluent/linter_config.yml.github/fluent_linter_config.yml renamed to .github/fluent/linter_config.yml

@@ -4,13 +4,14 @@ on:
     paths:
       - 'locales/en-US/*.ftl'
       - '.github/workflows/fluent_linter.yml'
+      - '.github/fluent/*'
     branches:
       - main
   pull_request:
     paths:
-      - 'en/**.ftl'
       - 'locales/en-US/*.ftl'
       - '.github/workflows/fluent_linter.yml'
+      - '.github/fluent/*'
     branches:
       - main
   workflow_dispatch:
@@ -27,7 +28,7 @@ jobs:
           cache: 'pip'
       - name: Install Python dependencies
         run: |
-          pip install -r .github/requirements.txt
+          pip install -r .github/fluent/requirements.txt
       - name: Lint reference
         run: |
-          moz-fluent-lint ./locales/en-US --config .github/fluent_linter_config.yml
+          moz-fluent-lint ./locales/en-US --config .github/fluent/linter_config.yml