FIR IDE: Enable add accessors quickfix for MUST_BE_INITIALIZED.

Also added diagnosticFixFactoriesFromIntentionActions() to share
quickfix-creation across multiple diagnostics with the same PSI.

idea/testData/quickfix/addPropertyAccessors/varHasGetter.kt

@@ -4,5 +4,4 @@ class Test {
         get() {
             return 1
         }
-}
-/* IGNORE_FIR */
+}

idea/testData/quickfix/addPropertyAccessors/varHasGetter.kt.after

@@ -5,5 +5,4 @@ class Test {
             return 1
         }
         set(value) {<caret>}
-}
-/* IGNORE_FIR */
+}

idea/testData/quickfix/addPropertyAccessors/varHasSetter.kt

@@ -3,5 +3,4 @@
 class Test {
     var x: Int<caret>
         set(value) {}
-}
-/* IGNORE_FIR */
+}

idea/testData/quickfix/addPropertyAccessors/varHasSetter.kt.after

@@ -6,5 +6,4 @@ class Test {
             <caret>TODO()
         }
         set(value) {}
-}
-/* IGNORE_FIR */
+}