Feature: Toggle Explorer Arrows Configuration (#8)

* fix: json format

fixes the json format to be made parseable by the default spec

* feat: base impl for the configuration change

adds in a command and it's respective function for over-riding the json

* remove command handling from the json

* feat: add a config monitor

helpers and implementation of a
configuration monitor for the keys defined in
package.json

* re-enable hideExplorer

* fix: remove trailing comma for json

* Update package-lock.json

* Remove trailing comma

* Show notification when setting changed

Co-authored-by: Miguel Solorio <miguel.solorio@microsoft.com>

.gitignore

@@ -3,3 +3,4 @@ dist
 node_modules
 .vscode-test/
 *.vsix
+src/symbol-icon-theme.modified.json