[file_selector] Remove Linux implementation (#907)

This plugin has been moved to flutter/plugins.

Also removes the old `file_chooser` README redirect, since
`file_selector` has now existed for quite a while, so `file_chooser`
references would be old enough that they aren't worth continuing to
handle.

Author: stuartmorgan

.github/ISSUE_TEMPLATE/BUG-REPORT.yml

@@ -17,7 +17,6 @@ body:
   attributes:
     label: Which plugin is this bug report about?
     options:
-      - file_selector
       - menubar
       - window_size
   validations:

.github/ISSUE_TEMPLATE/OTHER.yml

@@ -17,7 +17,6 @@ body:
   attributes:
     label: Which plugin is this request about?
     options:
-      - file_selector
       - menubar
       - window_size
       - A proposal for a new experimental plugin

.github/workflows/ci.yml

@@ -62,15 +62,3 @@ jobs:
         flutter packages get	
         flutter build -v ${{matrix.TARGET}} --release	
       working-directory: ${{ github.workspace }}/fde/testbed
-    - name: Build file_selector implementations debug	
-      if: startsWith(matrix.os, 'ubuntu')
-      run: |	
-        flutter packages get
-        flutter build -v ${{matrix.TARGET}} --debug	
-      working-directory: ${{ github.workspace }}/fde/plugins/file_selector/file_selector_linux/example	
-    - name: Build file_selector implementations release	
-      if: startsWith(matrix.os, 'ubuntu')
-      run: |	
-        flutter packages get	
-        flutter build -v ${{matrix.TARGET}} --release	
-      working-directory: ${{ github.workspace }}/fde/plugins/file_selector/file_selector_linux/example

plugins/README.md

@@ -12,10 +12,10 @@ you should include them directly from this repository:
 ```
 dependencies:
   ...
-  file_chooser:
+  menubar:
     git:
       url: https://github.com/google/flutter-desktop-embedding.git
-      path: plugins/file_chooser
+      path: plugins/menubar
       ref: INSERT_HASH_HERE
 ```