[oemid] Use consistent ${} substitution

SEE #1438

CHANGES-3.3

@@ -56,6 +56,8 @@ Pre-release versions:
    Please update configurations.
  - *mount* now does most of the mounting; options that were in *fstab*
    have moved here. See #1993
+ - *oemid* now uses consistent variable replacement (e.g. KMacroExpander)
+   and does not support `@@DATE@@` anymore (use `${DATE}`).
  - *partition* requires KPMCore 21.12 (e.g. KPMCore 4.2 API, or later).
  - *partition* can now skip installing the bootloader in more scenarios.
    #1632 (Thanks Anubhav)

src/modules/oemid/OEMViewStep.cpp

@@ -14,6 +14,7 @@
 #include "IDJob.h"
 
 #include "utils/Retranslator.h"
+#include "utils/StringExpander.h"
 #include "utils/Variant.h"
 
 #include <QDate>
@@ -82,14 +83,10 @@ OEMViewStep::isAtEnd() const
 static QString
 substitute( QString s )
 {
-    QString t_date = QStringLiteral( "@@DATE@@" );
-    if ( s.contains( t_date ) )
-    {
-        auto date = QDate::currentDate();
-        s = s.replace( t_date, date.toString( Qt::ISODate ) );
-    }
+    Calamares::String::DictionaryExpander d;
+    d.insert( QStringLiteral( "DATE" ), QDate::currentDate().toString( Qt::ISODate ) );
 
-    return s;
+    return d.expand( s );
 }
 
 void

src/modules/oemid/oemid.conf

@@ -5,12 +5,12 @@
 ---
 # The batch-identifier is written to /var/log/installer/oem-id.
 # This value is put into the text box as the **suggested**
-# OEM ID. If @@DATE@@ is included in the identifier, then
+# OEM ID. If ${DATE} is included in the identifier, then
 # that is replaced by the current date in yyyy-MM-dd (ISO) format.
 #
-# it is ok for the identifier to be empty.
+# It is ok for the identifier to be empty.
 #
 # The identifier is written to the file as UTF-8 (this will be no
 # different from ASCII, for most inputs) and followed by a newline.
 # If the identifier is empty, only a newline is written.
-batch-identifier: neon-@@DATE@@
+batch-identifier: neon-${DATE}