Rename BindableState to BindingState (#1855)

The -`able` naming evokes protocols in Swift, and is an outlier when
considered alongside the rest of TCA's binding tools:

- `BindingAction`: concrete type
- `BindableAction`: protocol
- `BindingReducer`: concrete type

So, let's make things consistent.

The one caveat is that Swift diagnostics for such a deprecation aren't
great, so users won't get proactive warnings here for the time being:

swiftlang/swift#63139

We may just want to keep the deprecation around till it does...

(cherry picked from commit 52c4a01437aa1429dab4e6b460062a8b7d6aeab6)

# Conflicts:
#	Sources/ComposableArchitecture/Internal/Deprecations.swift
#	Sources/ComposableArchitecture/SwiftUI/Binding.swift
#	Tests/ComposableArchitectureTests/DebugTests.swift

Author: stephencelis

Examples/CaseStudies/SwiftUICaseStudies/01-GettingStarted-Bindings-Forms.swift

@@ -8,7 +8,7 @@ private let readMe = """
   Bindable state and actions allow you to safely eliminate the boilerplate caused by needing to \
   have a unique action for every UI control. Instead, all UI bindings can be consolidated into a \
   single `binding` action that holds onto a `BindingAction` value, and all bindable state can be \
-  safeguarded with the `BindableState` property wrapper.
+  safeguarded with the `BindingState` property wrapper.
 
   It is instructive to compare this case study to the "Binding Basics" case study.
   """
@@ -17,10 +17,10 @@ private let readMe = """
 
 struct BindingForm: ReducerProtocol {
   struct State: Equatable {
-    @BindableState var sliderValue = 5.0
-    @BindableState var stepCount = 10
-    @BindableState var text = ""
-    @BindableState var toggleIsOn = false
+    @BindingState var sliderValue = 5.0
+    @BindingState var stepCount = 10
+    @BindingState var text = ""
+    @BindingState var toggleIsOn = false
   }
 
   enum Action: BindableAction, Equatable {

Examples/CaseStudies/SwiftUICaseStudies/01-GettingStarted-FocusState.swift

@@ -10,9 +10,9 @@ private let readMe = """
 
 struct FocusDemo: ReducerProtocol {
   struct State: Equatable {
-    @BindableState var focusedField: Field?
-    @BindableState var password: String = ""
-    @BindableState var username: String = ""
+    @BindingState var focusedField: Field?
+    @BindingState var password: String = ""
+    @BindingState var username: String = ""
 
     enum Field: String, Hashable {
       case username, password

Sources/ComposableArchitecture/Documentation.docc/Articles/Bindings.md

@@ -177,20 +177,20 @@ struct Settings: ReducerProtocol {
 ```
 
 This is a _lot_ of boilerplate for something that should be simple. Luckily, we can dramatically
-eliminate this boilerplate using ``BindableState``, ``BindableAction``, and ``BindingReducer``.
+eliminate this boilerplate using ``BindingState``, ``BindableAction``, and ``BindingReducer``.
 
-First, we can annotate each bindable value of state with the ``BindableState`` property wrapper:
+First, we can annotate each bindable value of state with the ``BindingState`` property wrapper:
 
 ```swift
 struct Settings: ReducerProtocol {
   struct State: Equatable {
-    @BindableState var digest = Digest.daily
-    @BindableState var displayName = ""
-    @BindableState var enableNotifications = false
+    @BindingState var digest = Digest.daily
+    @BindingState var displayName = ""
+    @BindingState var enableNotifications = false
     var isLoading = false
-    @BindableState var protectMyPosts = false
-    @BindableState var sendEmailNotifications = false
-    @BindableState var sendMobileNotifications = false
+    @BindingState var protectMyPosts = false
+    @BindingState var sendEmailNotifications = false
+    @BindingState var sendMobileNotifications = false
   }
 
   // ...

Sources/ComposableArchitecture/Documentation.docc/Extensions/SwiftUI.md

@@ -19,7 +19,7 @@ The Composable Architecture can be used to power applications built in many fram
 
 - <doc:Bindings>
 - ``ViewStore/binding(get:send:)-65xes``
-- ``BindableState``
+- ``BindingState``
 - ``BindableAction``
 - ``BindingAction``
 - ``BindingReducer``