Remove last 'rule' mentions in the exemptions handling

Remove those because from now instances and rules can be exempted.

Author: HugoGGuerrier

lkql_checker/src/gnatcheck-diagnoses.adb

@@ -2560,7 +2560,7 @@ package body Gnatcheck.Diagnoses is
                        To_String (Next_Postponed_Section
                                   .Exemption_Section
                                   .Exempted_Name) &
-                       " rule in exemption section starting at line" &
+                       " in exemption section starting at line" &
                        Next_Postponed_Section.Exemption_Section.Line_Start'Img,
                      Diagnosis_Kind => Exemption_Warning,
                      SF             => SF);
@@ -2598,7 +2598,7 @@ package body Gnatcheck.Diagnoses is
                             (Next_Par_S_Info.Exempt_Info.Exempted_Name) &
                           ": " & Params_Img
                             (Next_Par_S_Info.Params, Next_Par_S_Info.Rule) &
-                          "' rule in exemption section starting " & "at line" &
+                          "' in exemption section starting at line" &
                           Next_Par_S_Info.Exempt_Info.Line_Start'Img,
                         Diagnosis_Kind => Exemption_Warning,
                         SF             => SF);
@@ -2730,7 +2730,7 @@ package body Gnatcheck.Diagnoses is
                   Store_Diagnosis
                     (Text           => File_Name (SF) & ":" & SLOC &
                                        ": parameter " & Param &
-                                       " duplicated in rule exemption",
+                                       " duplicated in exemption",
                      Diagnosis_Kind => Exemption_Warning,
                      SF             => SF);
                end if;

testsuite/tests/gnatcheck/exemptions/comment_annotations_check/test.out

@@ -35,7 +35,7 @@ main.adb:20:16: expression function
 4. Rule exemption problems
 
 c.adb:1:01: no matching 'exempt_OFF' annotation for Goto_Statements
-c.adb:6:07: no detection for Goto_Statements rule in exemption section starting at line 1
+c.adb:6:07: no detection for Goto_Statements in exemption section starting at line 1
 main.adb:24:07: no matching 'exempt_OFF' annotation for expression_functions
 main.adb:29:04: rule expression_functions is already exempted at line 24
 main.adb:33:41: State should be "off" for line exemption

testsuite/tests/gnatcheck/exemptions/instance_exemptions/test.out

@@ -63,10 +63,10 @@ main.adb:27:04: wrong rule or instance name in exemption (Not_Existant), ignored
 main.adb:29:04: cannot exempt a specific instance of a compiler rule (style_checks), ignored
 main.adb:59:04: rule goto_statements is already exempted at line 58
 main.adb:60:04: rule goto_statements is already exempted at line 58
-main.adb:61:65: no detection for Goto_Statements rule in exemption section starting at line 58
+main.adb:61:65: no detection for Goto_Statements in exemption section starting at line 58
 main.adb:65:04: instance GOTO is already exempted at line 63
-main.adb:66:58: no detection for Goto_Statements rule in exemption section starting at line 64
-main.adb:67:58: no detection for GOTO rule in exemption section starting at line 63
+main.adb:66:58: no detection for Goto_Statements in exemption section starting at line 64
+main.adb:67:58: no detection for GOTO in exemption section starting at line 63
 main.adb:71:04: rule Style_Checks is already exempted with parameter(s) at line 69
 main.adb:72:04: rule Style_Checks is already exempted with parameter 'x' at line 69
 main.adb:73:04: rule Style_Checks is already exempted with the same parameter(s) at line 69

testsuite/tests/gnatcheck/exemptions/restriction_exemptions/test.out

@@ -24,7 +24,7 @@ main.adb:20:18: reference to "Ada.Text_IO.Put_Line" violates restriction No_Use_
 
 4. Rule exemption problems
 
-main.adb:22:106: no detection for 'Restrictions: Max_Protected_Entries, No_Access_Subprograms' rule in exemption section starting at line 17
+main.adb:22:106: no detection for 'Restrictions: Max_Protected_Entries, No_Access_Subprograms' in exemption section starting at line 17
 
 5. Language violations