Use const enums for minimized ISuggestDataDto types

From #71060

**Problem**
ISuggestDataDto currently uses opaque property names in order to keep the size of the json object down. This makes the code difficult to read

**Proposed Fix**
Use a const enum to map human readable property name to the short names actually used for the json

src/vs/workbench/api/common/extHost.protocol.ts

@@ -929,21 +929,38 @@ export class IdObject {
 	}
 }
 
+export const enum ISuggestDataDtoField {
+	label = 'a',
+	kind = 'b',
+	detail = 'c',
+	documentation = 'd',
+	sortText = 'e',
+	filterText = 'f',
+	preselect = 'g',
+	insertText = 'h',
+	insertTextRules = 'i',
+	range = 'j',
+	commitCharacters = 'k',
+	additionalTextEdits = 'l',
+	command = 'm',
+	kindModifier = 'n',
+}
+
 export interface ISuggestDataDto {
-	a/* label */: string;
-	b/* kind */: modes.CompletionItemKind;
-	c/* detail */?: string;
-	d/* documentation */?: string | IMarkdownString;
-	e/* sortText */?: string;
-	f/* filterText */?: string;
-	g/* preselect */?: boolean;
-	h/* insertText */?: string;
-	i/* insertTextRules */?: modes.CompletionItemInsertTextRule;
-	j/* range */?: IRange;
-	k/* commitCharacters */?: string[];
-	l/* additionalTextEdits */?: ISingleEditOperation[];
-	m/* command */?: modes.Command;
-	n/* kindModifier */?: modes.CompletionItemTag[];
+	[ISuggestDataDtoField.label]: string;
+	[ISuggestDataDtoField.kind]: modes.CompletionItemKind;
+	[ISuggestDataDtoField.detail]?: string;
+	[ISuggestDataDtoField.documentation]?: string | IMarkdownString;
+	[ISuggestDataDtoField.sortText]?: string;
+	[ISuggestDataDtoField.filterText]?: string;
+	[ISuggestDataDtoField.preselect]?: boolean;
+	[ISuggestDataDtoField.insertText]?: string;
+	[ISuggestDataDtoField.insertTextRules]?: modes.CompletionItemInsertTextRule;
+	[ISuggestDataDtoField.range]?: IRange;
+	[ISuggestDataDtoField.commitCharacters]?: string[];
+	[ISuggestDataDtoField.additionalTextEdits]?: ISingleEditOperation[];
+	[ISuggestDataDtoField.command]?: modes.Command;
+	[ISuggestDataDtoField.kindModifier]?: modes.CompletionItemTag[];
 	// not-standard
 	x?: ChainedCacheId;
 }