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

compiler/psi/src/org/jetbrains/kotlin/kdoc/parser/KDocKnownTag.kt

@@ -16,6 +16,8 @@
 
 package org.jetbrains.kotlin.kdoc.parser
 
+import org.jetbrains.kotlin.util.capitalizeDecapitalize.toUpperCaseAsciiOnly
+
 enum class KDocKnownTag(val isReferenceRequired: Boolean, val isSectionStart: Boolean) {
     AUTHOR(false, false),
     THROWS(true, false),
@@ -37,7 +39,7 @@ enum class KDocKnownTag(val isReferenceRequired: Boolean, val isSectionStart: Bo
                 tagName.subSequence(1, tagName.length)
             } else tagName
             try {
-                return valueOf(name.toString().toUpperCase())
+                return valueOf(name.toString().toUpperCaseAsciiOnly())
             } catch (ignored: IllegalArgumentException) {
             }
 

compiler/psi/src/org/jetbrains/kotlin/kdoc/psi/impl/KDocImpl.kt

@@ -10,13 +10,14 @@ import com.intellij.psi.impl.source.tree.LazyParseablePsiElement
 import com.intellij.psi.tree.IElementType
 import org.jetbrains.kotlin.idea.KotlinLanguage
 import org.jetbrains.kotlin.kdoc.lexer.KDocTokens
+import org.jetbrains.kotlin.kdoc.parser.KDocKnownTag
 import org.jetbrains.kotlin.kdoc.psi.api.KDoc
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.KtDeclaration
-import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
 import org.jetbrains.kotlin.psi.psiUtil.getChildOfType
 import org.jetbrains.kotlin.psi.psiUtil.getChildrenOfType
-import org.jetbrains.kotlin.kdoc.parser.KDocKnownTag
+import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
+import org.jetbrains.kotlin.util.capitalizeDecapitalize.toLowerCaseAsciiOnly
 
 class KDocImpl(buffer: CharSequence?) : LazyParseablePsiElement(KDocTokens.KDOC, buffer), KDoc {
 
@@ -37,10 +38,10 @@ class KDocImpl(buffer: CharSequence?) : LazyParseablePsiElement(KDocTokens.KDOC,
         getChildrenOfType<KDocSection>().firstOrNull { it.name == name }
 
     override fun findSectionByTag(tag: KDocKnownTag): KDocSection? =
-        findSectionByName(tag.name.toLowerCase())
+        findSectionByName(tag.name.toLowerCaseAsciiOnly())
 
     override fun findSectionByTag(tag: KDocKnownTag, subjectName: String): KDocSection? =
         getChildrenOfType<KDocSection>().firstOrNull {
-            it.name == tag.name.toLowerCase() && it.getSubjectName() == subjectName
+            it.name == tag.name.toLowerCaseAsciiOnly() && it.getSubjectName() == subjectName
         }
 }