More renaming

Avoid usage of "Feature Flag" unless we are talking specifically about
the response from github features api. Otherwise, use terms like
"Toggleable features".

Note both "toggleable" and "togglable" appear to be valid spellings of
the word. I chose the first for no good reason.

src/autobuild.ts

@@ -1,13 +1,13 @@
 import { getCodeQL } from "./codeql";
 import * as configUtils from "./config-utils";
-import { FeatureFlags } from "./feature-flags";
+import { FeatureEnablement } from "./feature-flags";
 import { Language, isTracedLanguage } from "./languages";
 import { Logger } from "./logging";
 import * as util from "./util";
 
 export async function determineAutobuildLanguages(
   config: configUtils.Config,
-  featureFlags: FeatureFlags,
+  featureFlags: FeatureEnablement,
   logger: Logger
 ): Promise<Language[] | undefined> {
   const isGoExtractionReconciliationEnabled =