Fix double quotes in diagnostic messages

For diagnostics without any parameters, the given text is simply rendered as a
String, so no symbols should be escaped.

For diagnostics with parameters, the format in java.text.MessageFormat is used,
so one single quote is erased and two single quotes become one single quote in
the rendered text.

idea/testData/checker/WhenNonExhaustive.kt

@@ -1,12 +1,12 @@
-fun nonExhaustiveInt(x: Int) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'else' branch">when</error>(x) {
+fun nonExhaustiveInt(x: Int) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'else' branch">when</error>(x) {
     0 -> false
 }
 
-fun nonExhaustiveBoolean(b: Boolean) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'true' branch or 'else' branch instead">when</error>(b) {
+fun nonExhaustiveBoolean(b: Boolean) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'true' branch or 'else' branch instead">when</error>(b) {
     false -> 0
 }
 
-fun nonExhaustiveNullableBoolean(b: Boolean?) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'null' branch or 'else' branch instead">when</error>(b) {
+fun nonExhaustiveNullableBoolean(b: Boolean?) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'null' branch or 'else' branch instead">when</error>(b) {
     false -> 0
     true -> 1
 }
@@ -17,17 +17,17 @@ enum class Color {
     BLUE
 }
 
-fun nonExhaustiveEnum(c: Color) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'RED', 'BLUE' branches or 'else' branch instead">when</error>(c) {
+fun nonExhaustiveEnum(c: Color) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'RED', 'BLUE' branches or 'else' branch instead">when</error>(c) {
     Color.GREEN -> 0xff00
 }
 
-fun nonExhaustiveNullable(c: Color?) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'GREEN', 'null' branches or 'else' branch instead">when</error>(c) {
+fun nonExhaustiveNullable(c: Color?) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'GREEN', 'null' branches or 'else' branch instead">when</error>(c) {
     Color.RED -> 0xff
     Color.BLUE -> 0xff0000
 }
 
 fun whenOnEnum(c: Color) {
-    <warning descr="[NON_EXHAUSTIVE_WHEN] when expression on enum is recommended to be exhaustive, add 'RED' branch or 'else' branch instead">when</warning>(c) {
+    <warning descr="[NON_EXHAUSTIVE_WHEN] 'when' expression on enum is recommended to be exhaustive, add 'RED' branch or 'else' branch instead">when</warning>(c) {
         Color.BLUE -> {}
         Color.GREEN -> {}
     }
@@ -37,7 +37,7 @@ enum class EnumInt {
     A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15
 }
 
-fun whenOnLongEnum(i: EnumInt) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'A0', 'A1', 'A2', 'A3', 'A4', 'A5', 'A6', ... branches or 'else' branch instead">when</error> (i) {
+fun whenOnLongEnum(i: EnumInt) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'A0', 'A1', 'A2', 'A3', 'A4', 'A5', 'A6', ... branches or 'else' branch instead">when</error> (i) {
     EnumInt.A7 -> 7
 }
 
@@ -49,17 +49,17 @@ sealed class Variant {
     object Another : Variant()
 }
 
-fun nonExhaustiveSealed(v: Variant) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'is Something', 'Another' branches or 'else' branch instead">when</error>(v) {
+fun nonExhaustiveSealed(v: Variant) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'is Something', 'Another' branches or 'else' branch instead">when</error>(v) {
     Variant.Singleton -> false
 }
 
-fun nonExhaustiveNullableSealed(v: Variant?) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'Another', 'null' branches or 'else' branch instead">when</error>(v) {
+fun nonExhaustiveNullableSealed(v: Variant?) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'Another', 'null' branches or 'else' branch instead">when</error>(v) {
     Variant.Singleton -> false
     is Variant.Something -> true
 }
 
 sealed class Empty
 
-fun nonExhaustiveEmpty(e: Empty) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'else' branch">when</error>(<warning>e</warning>) {}
+fun nonExhaustiveEmpty(e: Empty) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'else' branch">when</error>(<warning>e</warning>) {}
 
-fun nonExhaustiveNullableEmpty(e: Empty?) = <error descr="[NO_ELSE_IN_WHEN] when expression must be exhaustive, add necessary 'else' branch">when</error>(<warning>e</warning>) {}
+fun nonExhaustiveNullableEmpty(e: Empty?) = <error descr="[NO_ELSE_IN_WHEN] 'when' expression must be exhaustive, add necessary 'else' branch">when</error>(<warning>e</warning>) {}