go/packages: undeprecate Load* style flags

Updates golang/go#70470

Change-Id: Ia254b993b301fcc708d07b3773fad31a971c5997
Reviewed-on: https://go-review.googlesource.com/c/tools/+/630435
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

go/packages/packages.go

@@ -43,6 +43,20 @@ import (
 // ID and Errors (if present) will always be filled.
 // [Load] may return more information than requested.
 //
+// The Mode flag is a union of several bits named NeedName,
+// NeedFiles, and so on, each of which determines whether
+// a given field of Package (Name, Files, etc) should be
+// populated.
+//
+// For convenience, we provide named constants for the most
+// common combinations of Need flags:
+//
+//	[LoadFiles]     lists of files in each package
+//	[LoadImports]   ... plus imports
+//	[LoadTypes]     ... plus type information
+//	[LoadSyntax]    ... plus type-annotated syntax
+//	[LoadAllSyntax] ... for all dependencies
+//
 // Unfortunately there are a number of open bugs related to
 // interactions among the LoadMode bits:
 //   - https://github.com/golang/go/issues/56633
@@ -109,33 +123,18 @@ const (
 
 const (
 	// LoadFiles loads the name and file names for the initial packages.
-	//
-	// Deprecated: LoadFiles exists for historical compatibility
-	// and should not be used. Please directly specify the needed fields using the Need values.
 	LoadFiles = NeedName | NeedFiles | NeedCompiledGoFiles
 
 	// LoadImports loads the name, file names, and import mapping for the initial packages.
-	//
-	// Deprecated: LoadImports exists for historical compatibility
-	// and should not be used. Please directly specify the needed fields using the Need values.
 	LoadImports = LoadFiles | NeedImports
 
 	// LoadTypes loads exported type information for the initial packages.
-	//
-	// Deprecated: LoadTypes exists for historical compatibility
-	// and should not be used. Please directly specify the needed fields using the Need values.
 	LoadTypes = LoadImports | NeedTypes | NeedTypesSizes
 
 	// LoadSyntax loads typed syntax for the initial packages.
-	//
-	// Deprecated: LoadSyntax exists for historical compatibility
-	// and should not be used. Please directly specify the needed fields using the Need values.
 	LoadSyntax = LoadTypes | NeedSyntax | NeedTypesInfo
 
 	// LoadAllSyntax loads typed syntax for the initial packages and all dependencies.
-	//
-	// Deprecated: LoadAllSyntax exists for historical compatibility
-	// and should not be used. Please directly specify the needed fields using the Need values.
 	LoadAllSyntax = LoadSyntax | NeedDeps
 
 	// Deprecated: NeedExportsFile is a historical misspelling of NeedExportFile.