fix: add file context override for inline completion (#660)

## Problem

Support of inline completion in JL Notebook is gone since the language
server migration.
aws/aws-toolkit-vscode#7086

## Solution

Let the IDE provide the file context. 

There is a technical limitations of the language server that it cannot
find or construct the `vscode.NotebookDocument`, `vscode.NotebookCell`.
The `workspace.getTextDocument` does not work with JL Notebook as it
gets a URI in the format of
"`vscode-notebook-cell:/../A1.ipynb#W2sZmlsZQ%3D%3D`". The language
server does not have the cell number, cell state, cursor position, etc
of the current cell.

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## License

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

Author: leigaol

runtimes/protocol/inlineCompletionWithReferences.ts

@@ -21,10 +21,23 @@ interface OpenTabParams {
     openTabFilepaths?: string[]
 }
 
+interface FileContext {
+    leftFileContent: string
+    rightFileContent: string
+    filename: string
+    fileUri?: string
+    programmingLanguage: string
+}
+
+interface FileContextParams {
+    fileContextOverride?: FileContext
+}
+
 export type InlineCompletionWithReferencesParams = InlineCompletionParams &
     PartialResultParams &
     DocumentChangeParams &
-    OpenTabParams
+    OpenTabParams &
+    FileContextParams
 
 export const inlineCompletionWithReferencesRequestType = new ProtocolRequestType<
     InlineCompletionWithReferencesParams,