Context: add three new experimental retriever strategies (#5494)

# Context
The PR adds three major context sources useful for autocomplete and
next-edit-suggestion.

### Recent Copy retriever.

Developers often copy/cut and paste context and before pasting we show
autocomplete suggestions to the user. The PR leverages the copied
content on the clipboard by the user as a context source.
I wasn't able to find any vscode api event exposed which triggers when
user `copy` or `cut` text in the editor. This seems like an open issue:
microsoft/vscode#30066

Another alternative I think of is to use a keybinding of `Ctrl+x` and
`Ctrl+c`, but not fully sure about its implications, since this is one
of the most common shortcuts.

As a workaround, The way current PR accomplishes the same is:
1. Tracks the selection made by the user in the last `1 minutes` and
keeps tracks of upto `100` most recent selections.
3. At the time of retrieval, checks if the current clipboard content
matches the selection items in the list.

### Recent View Ports
This context source captures and utilizes the recently viewed portions
of code in the editor. It keeps track of the visible areas of code that
the developer has scrolled through or focused on within a specified time
frame.

### Diagnostics 
The Diagnostics context source leverages the diagnostic information
provided by VS Code and language servers. It collects and utilizes
information about errors, for a file as a context source.

## Test plan
1. Automated test 
- Added CI tests for each of the retrievers

2. Manual test
- Override the setting `"cody.autocomplete.experimental.graphContext":
"recent-copy"` in vscode settings.
- Observe the context events using `Autocomplete Trace View`

vscode/src/completions/completion-provider-config.ts

@@ -44,6 +44,9 @@ class CompletionProviderConfig {
             'recent-edits-1m',
             'recent-edits-5m',
             'recent-edits-mixed',
+            'recent-copy',
+            'diagnostics',
+            'recent-view-port',
         ]
         return resolvedConfig.pipe(
             mergeMap(({ configuration }) => {

vscode/src/completions/context/context-strategy.ts

@@ -10,7 +10,10 @@ import type { ContextRetriever } from '../types'
 import type { BfgRetriever } from './retrievers/bfg/bfg-retriever'
 import { JaccardSimilarityRetriever } from './retrievers/jaccard-similarity/jaccard-similarity-retriever'
 import { LspLightRetriever } from './retrievers/lsp-light/lsp-light-retriever'
-import { RecentEditsRetriever } from './retrievers/recent-edits/recent-edits-retriever'
+import { DiagnosticsRetriever } from './retrievers/recent-user-actions/diagnostics-retriever'
+import { RecentCopyRetriever } from './retrievers/recent-user-actions/recent-copy'
+import { RecentEditsRetriever } from './retrievers/recent-user-actions/recent-edits-retriever'
+import { RecentViewPortRetriever } from './retrievers/recent-user-actions/recent-view-port'
 import { loadTscRetriever } from './retrievers/tsc/load-tsc-retriever'
 
 export type ContextStrategy =
@@ -26,6 +29,9 @@ export type ContextStrategy =
     | 'recent-edits-1m'
     | 'recent-edits-5m'
     | 'recent-edits-mixed'
+    | 'recent-copy'
+    | 'diagnostics'
+    | 'recent-view-port'
 
 export interface ContextStrategyFactory extends vscode.Disposable {
     getStrategy(
@@ -82,6 +88,18 @@ export class DefaultContextStrategyFactory implements ContextStrategyFactory {
                             this.localRetriever = new JaccardSimilarityRetriever()
                             this.graphRetriever = new LspLightRetriever()
                             break
+                        case 'recent-copy':
+                            this.localRetriever = new RecentCopyRetriever({
+                                maxAgeMs: 60 * 1000,
+                                maxSelections: 100,
+                            })
+                            break
+                        case 'diagnostics':
+                            this.localRetriever = new DiagnosticsRetriever()
+                            break
+                        case 'recent-view-port':
+                            this.localRetriever = new RecentViewPortRetriever()
+                            break
                         case 'jaccard-similarity':
                             this.localRetriever = new JaccardSimilarityRetriever()
                             break
@@ -148,7 +166,10 @@ export class DefaultContextStrategyFactory implements ContextStrategyFactory {
             case 'jaccard-similarity':
             case 'recent-edits':
             case 'recent-edits-1m':
-            case 'recent-edits-5m': {
+            case 'recent-edits-5m':
+            case 'recent-copy':
+            case 'diagnostics':
+            case 'recent-view-port': {
                 if (this.localRetriever) {
                     retrievers.push(this.localRetriever)
                 }