fix incorrect typing on Diagnostics, and add missing fields to the codeaction context

Author: baronfel

src/Types.fs

@@ -1721,7 +1721,7 @@ type Diagnostic =
 
     /// A human-readable string describing the source of this
     /// diagnostic, e.g. 'typescript' or 'super lint'.
-    Source: string
+    Source: string option
 
     /// The diagnostic's message.
     Message: string
@@ -1939,11 +1939,27 @@ type ColorPresentation =
     /// selecting this color presentation. Edits must not overlap with the main edit nor with themselves.
     AdditionalTextEdits: TextEdit [] option }
 
+type CodeActionKind = string
+
+type CodeActionTriggerKind =
+/// Code actions were explicitly requested by the user or by an extension.
+| Invoked = 1
+/// Code actions were requested automatically.
+/// This typically happens when current selection in a file changes, but can also be triggered when file content changes.
+| Automatic = 2
+
 /// Contains additional diagnostic information about the context in which
 /// a code action is run.
 type CodeActionContext =
   { /// An array of diagnostics.
-    Diagnostics: Diagnostic [] }
+    Diagnostics: Diagnostic []
+    /// Requested kind of actions to return.
+    /// Actions not of this kind are filtered out by the client before being
+    /// shown. So servers can omit computing them.
+    Only: CodeActionKind [] option
+    /// The reason why code actions were requested.
+    /// @since 3.17.0
+    TriggerKind: CodeActionTriggerKind option }
 
 /// Params for the CodeActionRequest
 type CodeActionParams =