[AST] Demote inout to a SWIFT_KEYWORD

Defining it as a `DECL_KEYWORD` means code
completion will try and complete it in decl
position. It shouldn't really be considered a decl
keyword, so define it as `SWIFT_KEYWORD`.

Author: hamishknight

include/swift/AST/TokenKinds.def

@@ -145,7 +145,6 @@ DECL_KEYWORD(extension)
 DECL_KEYWORD(func)
 DECL_KEYWORD(import)
 DECL_KEYWORD(init)
-DECL_KEYWORD(inout)
 DECL_KEYWORD(let)
 DECL_KEYWORD(operator)
 DECL_KEYWORD(precedencegroup)
@@ -259,8 +258,9 @@ MISC(string_interpolation_anchor)
 MISC(kw_yield)
 MISC(kw_discard)
 MISC(kw_then)
+SWIFT_KEYWORD(inout)
 
-// The following tokens are irrelevant for swiftSyntax and thus only declared 
+// The following tokens are irrelevant for swiftSyntax and thus only declared
 // in this .def file
 
 SIL_KEYWORD(undef)

test/IDE/complete_at_top_level_library.swift

@@ -19,7 +19,6 @@ protocol MyProtocol {}
 // LIBRARY-DAG: Keyword[func]/None:                 func; name=func
 // LIBRARY-DAG: Keyword[import]/None:               import; name=import
 // LIBRARY-DAG: Keyword[init]/None:                 init; name=init
-// LIBRARY-DAG: Keyword[inout]/None:                inout; name=inout
 // LIBRARY-DAG: Keyword[operator]/None:             operator; name=operator
 // LIBRARY-DAG: Keyword[precedencegroup]/None:      precedencegroup; name=precedencegroup
 // LIBRARY-DAG: Keyword[protocol]/None/Flair[CommonKeyword]: protocol; name=protocol
@@ -86,7 +85,6 @@ protocol MyProtocol {}
 // SCRIPT-DAG: Keyword[func]/None:                 func; name=func
 // SCRIPT-DAG: Keyword[import]/None:               import; name=import
 // SCRIPT-DAG: Keyword[init]/None:                 init; name=init
-// SCRIPT-DAG: Keyword[inout]/None:                inout; name=inout
 // SCRIPT-DAG: Keyword[operator]/None:             operator; name=operator
 // SCRIPT-DAG: Keyword[precedencegroup]/None:      precedencegroup; name=precedencegroup
 // SCRIPT-DAG: Keyword[protocol]/None:             protocol; name=protocol

test/IDE/complete_keywords.swift

@@ -6,6 +6,8 @@
 // KW_IN: Keyword[in]/None: in{{; name=.+$}}
 // KW_NO_IN-NOT: Keyword[in]
 
+// KW_NO_INOUT-NOT: Keyword[inout]
+
 // KW_DECL-DAG: Keyword[class]/None: class{{; name=.+$}}
 // KW_DECL-DAG: Keyword/None: actor{{; name=.+$}}
 // KW_DECL-DAG: Keyword/None: convenience{{; name=.+$}}
@@ -293,7 +295,7 @@
 // KW_EXPR_NEG-NOT: Keyword{{.*}}catch
 // KW_EXPR_NEG-NOT: Keyword{{.*}}break
 
-#^TOP_LEVEL_1?check=KW_DECL_STMT_TOPLEVEL;check=KW_NO_RETURN;check=KW_NO_IN^#
+#^TOP_LEVEL_1?check=KW_DECL_STMT_TOPLEVEL;check=KW_NO_RETURN;check=KW_NO_IN;check=KW_NO_INOUT^#
 
 for _ in 1...10 {
   #^TOP_LEVEL_2?check=KW_DECL_STMT;check=KW_NO_RETURN;check=KW_NO_IN^#
@@ -367,19 +369,19 @@ struct InInit {
 }
 
 struct InStruct {
-  #^IN_NOMINAL_DECL_1?check=KW_DECL_TYPECONTEXT^#
+  #^IN_NOMINAL_DECL_1?check=KW_DECL_TYPECONTEXT;check=KW_NO_INOUT^#
 }
 
 enum InEnum {
-  #^IN_NOMINAL_DECL_2?check=KW_DECL_TYPECONTEXT^#
+  #^IN_NOMINAL_DECL_2?check=KW_DECL_TYPECONTEXT;check=KW_NO_INOUT^#
 }
 
 class InClass {
-  #^IN_NOMINAL_DECL_3?check=KW_DECL_TYPECONTEXT^#
+  #^IN_NOMINAL_DECL_3?check=KW_DECL_TYPECONTEXT;check=KW_NO_INOUT^#
 }
 
 protocol InProtocol {
-  #^IN_NOMINAL_DECL_4?check=KW_DECL_PROTOCOL^#
+  #^IN_NOMINAL_DECL_4?check=KW_DECL_PROTOCOL;check=KW_NO_INOUT^#
 }
 
 struct AfterOtherKeywords1 {