Editorial: Standardize the spelling of "uppercase" and "lowercase"

Matches Unicode:
* https://unicode.org/glossary/
* http://www.unicode.org/reports/tr18/
* http://www.unicode.org/unicode/reports/tr21
* https://www.unicode.org/reports/tr31

Ref tc39/ecma262#2598

spec/locale-sensitive-functions.html

@@ -89,10 +89,10 @@ <h1>
           1. If _locale_ is *undefined*, set _locale_ to *"und"*.
           1. Let _codePoints_ be ! StringToCodePoints(_S_).
           1. If _targetCase_ is ~lower~, then
-            1. Let _newCodePoints_ be a List whose elements are the result of a lower case transformation of _codePoints_ according to an implementation-derived algorithm using _locale_ or the Unicode Default Case Conversion algorithm.
+            1. Let _newCodePoints_ be a List whose elements are the result of a lowercase transformation of _codePoints_ according to an implementation-derived algorithm using _locale_ or the Unicode Default Case Conversion algorithm.
           1. Else,
             1. Assert: _targetCase_ is ~upper~.
-            1. Let _newCodePoints_ be a List whose elements are the result of an upper case transformation of _codePoints_ according to an implementation-derived algorithm using _locale_ or the Unicode Default Case Conversion algorithm.
+            1. Let _newCodePoints_ be a List whose elements are the result of an uppercase transformation of _codePoints_ according to an implementation-derived algorithm using _locale_ or the Unicode Default Case Conversion algorithm.
           1. Return ! CodePointsToString(_newCodePoints_).
         </emu-alg>
 

spec/locales-currencies-tz.html

@@ -136,7 +136,7 @@ <h1>DefaultLocale ( )</h1>
     <h1>Currency Codes</h1>
 
     <p>
-      The ECMAScript 2022 Internationalization API Specification identifies currencies using 3-letter currency codes as defined by ISO 4217. Their canonical form is upper case.
+      The ECMAScript 2022 Internationalization API Specification identifies currencies using 3-letter currency codes as defined by ISO 4217. Their canonical form is uppercase.
     </p>
 
     <p>

spec/numberformat.html

@@ -482,7 +482,7 @@ <h1>Abstract Operations for NumberFormat Objects</h1>
       <h1>CurrencyDigits ( _currency_ )</h1>
 
       <p>
-        When the CurrencyDigits abstract operation is called with an argument _currency_ (which must be an upper case String value), the following steps are taken:
+        When the CurrencyDigits abstract operation is called with an argument _currency_ (which must be an uppercase String value), the following steps are taken:
       </p>
 
       <emu-alg>