Request path completions from nearest / or \

Fixes microsoft#223414

Author: Tyriar

src/vs/workbench/contrib/terminal/browser/media/shellIntegration.ps1

@@ -245,6 +245,17 @@ function Send-Completions {
 				$cursorIndex = $newCursorIndex
 			}
 		}
+		# If it contains `/` or `\`, get completions from the nearest `/` or `\` such that file
+		# completions are consistent regardless of where it was requested
+		elseif ($lastWord -match '[/\\]') {
+			$lastSlashIndex = $completionPrefix.LastIndexOfAny(@('/', '\'))
+			if ($lastSlashIndex -ne -1 && $lastSlashIndex -lt $cursorIndex) {
+				$newCursorIndex = $lastSlashIndex + 1
+				$completionPrefix = $completionPrefix.Substring(0, $newCursorIndex)
+				$prefixCursorDelta = $cursorIndex - $newCursorIndex
+				$cursorIndex = $newCursorIndex
+			}
+		}
 
 		# Get completions using TabExpansion2
 		$completions = TabExpansion2 -inputScript $completionPrefix -cursorColumn $cursorIndex
@@ -293,6 +304,17 @@ function Send-Completions {
 	# If there is no space, get completions using CompletionCompleters as it gives us more
 	# control and works on the empty string
 	else {
+		# If it contains `/` or `\`, get completions from the nearest `/` or `\` such that file
+		# completions are consistent regardless of where it was requested
+		if ($completionPrefix -match '[/\\]') {
+			$lastSlashIndex = $completionPrefix.LastIndexOfAny(@('/', '\'))
+			if ($lastSlashIndex -ne -1 && $lastSlashIndex -lt $cursorIndex) {
+				$newCursorIndex = $lastSlashIndex + 1
+				$completionPrefix = $completionPrefix.Substring(0, $newCursorIndex)
+				$prefixCursorDelta = $cursorIndex - $newCursorIndex
+				$cursorIndex = $newCursorIndex
+			}
+		}
 		# Note that CompleteCommand isn't included here as it's expensive
 		$completions = $(
 			# Add trailing \ for directories so behavior aligns with TabExpansion2