Avoid unnecessary buildInfo read if host supports caching it (avoids in --build scenario) and some reporting cleanup (#51403)

* Emit diagnostics when just manipuating bundle at that time itself
[4:04:42 PM] Updating output of project '/TypeScript/src/tsserver/tsconfig.json'...

Memory used:        581215K
transformTime time:   0.01s
Source Map time:      0.35s
commentTime time:     0.00s
printTime time:       0.58s
Emit time:            0.90s
I/O Write time:       0.01s
Total time:           0.90s

* Pull out getSourceFile and writeFile in a function

* Fix incorrect solutionPerformance reporting in watch mode

* Remove unnecessary build info read when host can give cached buildInfo

* Simplify overloads

* Accept API change

src/compiler/types.ts

@@ -7234,6 +7234,7 @@ namespace ts {
         // For testing:
         /*@internal*/ disableUseFileVersionAsSignature?: boolean;
         /*@internal*/ storeFilesChangingSignatureDuringEmit?: boolean;
+        /*@internal*/ getBuildInfo?(fileName: string, configFilePath: string | undefined): BuildInfo | undefined;
     }
 
     /** true if --out otherwise source file name */