Add IGListBindingSingleSectionController to public headers

Summary:
While the `IGListBindingSingleSectionController` class and a nearly complete test suite were present in the IGListKit repo, they weren't imported into Xcode, and so they weren't part of the public release or the test CI.

Since the class looks like it's being used within Instagram, it's clear that it's not deprecated. I'm assuming it was added for a specific use-case in Instagram, and integrating it with the public Xcode project was still pending.

This diff integrates the class back into the public framework.

Reviewed By: candance

Differential Revision: D45147758

fbshipit-source-id: b0a84a2909635a4448480246f315243f4fcac134

Source/IGListKit/IGListBindingSingleSectionController.h

@@ -7,8 +7,7 @@
 
 #import <UIKit/UIKit.h>
 
-#import <IGListDiffKit/IGListMacros.h>
-#import <IGListKit/IGListSectionController.h>
+#import "IGListSectionController.h"
 
 NS_ASSUME_NONNULL_BEGIN
 

Source/IGListKit/IGListKit.h

@@ -36,6 +36,7 @@ FOUNDATION_EXPORT const unsigned char IGListKitVersionString[];
 #import "IGListBindingSectionController.h"
 #import "IGListBindingSectionControllerDataSource.h"
 #import "IGListBindingSectionControllerSelectionDelegate.h"
+#import "IGListBindingSingleSectionController.h"
 #import "IGListCollectionContext.h"
 #import "IGListCollectionView.h"
 #import "IGListCollectionViewLayout.h"

scripts/generate_spm_sources_layout.sh

@@ -114,7 +114,6 @@ function generate_ig_list_kit_spm_public_headers() {
 
     public_headers_list=$(
         find "Source/IGListKit" \
-        \! -name "IGListBindingSingleSectionController.[hm]" \
         -name "*.[h]" \
         -type f -not -path "spm/*" \
         -not -path "Source/IGListKit/Internal/*" \
@@ -177,7 +176,6 @@ function generate_ig_list_kit_spm_sources() {
 
     sources_list=$(
         find "Source/IGListKit" \
-        \! -name "IGListBindingSingleSectionController.[hm]" \
         -name "*.m" -o -name "*.mm" \
         -type f -not -path "spm/*" \
         -not -path "Examples/*" | sed "s| \([^/]\)|:\1|g")