Capitalize/decapitalize only ASCII characters across project

Use {de,}capitalizeAsciiOnly and to{Lower,Upper}CaseAsciiOnly where
possible, and stdlib's functions with Locale.US everywhere else.

Otherwise, if the default system locale is Turkish, the capital latin
letter "I" is transformed in toLowerCase to "ı" (see
https://github.com/JetBrains/kotlin/blob/66bc142f92085047a1ca64f9a291f0496e33dd98/libraries/stdlib/jvm/test/text/StringJVMTest.kt#L119),
which for example breaks the codegen for `intArrayOf` in
KT-25400/KT-43405.

Similarly, lower case latin letter "i" is transformed to "İ".

 #KT-13631 Fixed
 #KT-25400 Fixed
 #KT-43405 Fixed

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/KDocCompletionContributor.kt

@@ -43,6 +43,7 @@ import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.scopes.DescriptorKindFilter
 import org.jetbrains.kotlin.resolve.scopes.utils.collectDescriptorsFiltered
+import java.util.*
 
 class KDocCompletionContributor : CompletionContributor() {
     init {
@@ -157,7 +158,7 @@ object KDocTagCompletionProvider : CompletionProvider<CompletionParameters>() {
         val resultWithPrefix = result.withPrefixMatcher(prefix)
         KDocKnownTag.values().forEach {
             if (kdocOwner == null || it.isApplicable(kdocOwner)) {
-                resultWithPrefix.addElement(LookupElementBuilder.create("@" + it.name.toLowerCase()))
+                resultWithPrefix.addElement(LookupElementBuilder.create("@" + it.name.toLowerCase(Locale.US)))
             }
         }
     }

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/VariableOrParameterNameWithTypeCompletion.kt

@@ -24,7 +24,6 @@ import com.intellij.openapi.progress.ProgressManager
 import com.intellij.openapi.util.Key
 import com.intellij.psi.PsiClass
 import com.intellij.psi.PsiElement
-import com.intellij.psi.codeStyle.CodeStyleSettingsManager
 import com.intellij.psi.codeStyle.NameUtil
 import org.jetbrains.kotlin.descriptors.ClassifierDescriptor
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
@@ -69,7 +68,7 @@ class VariableOrParameterNameWithTypeCompletion(
             prefixWords.indices.map { index -> if (index == 0) prefix else prefixWords.drop(index).joinToString("") }
 
         userPrefixes = nameSuggestionPrefixes.indices.map { prefixWords.take(it).joinToString("") }
-        classNamePrefixMatchers = nameSuggestionPrefixes.map { CamelHumpMatcher(it.capitalize(), false) }
+        classNamePrefixMatchers = nameSuggestionPrefixes.map { CamelHumpMatcher(it.capitalize(Locale.US), false) }
     }
 
     private val suggestionsByTypesAdded = HashSet<Type>()
@@ -281,4 +280,4 @@ class VariableOrParameterNameWithTypeCompletion(
     object Weigher : LookupElementWeigher("kotlin.parameterNameAndTypePriority") {
         override fun weigh(element: LookupElement, context: WeighingContext): Int = element.getUserData(PRIORITY_KEY) ?: 0
     }
-}
+}