Kate syntax: allow PHP heredoc closing identifiers to be idented

It is allowed syntax since PHP version 7.3.0.

See https://www.php.net/manual/en/language.types.string.php#language.types.string.syntax.heredoc

Signed-off-by: Mavridis Philippe <mavridisf@gmail.com>
(cherry picked from commit b1fd9e80b3)

kate/data/php.xml

@@ -5542,27 +5542,27 @@ Changes:
         <DetectChar attribute="String" context="#pop" char="'" />
       </context>
       <context name="htmlheredoc" attribute="Normal Text" lineEndContext="#stay" dynamic="true">
-        <RegExpr attribute="Backslash Code" context="#pop" String="^%1;?$" dynamic="true" endRegion="Heredoc" />
+        <RegExpr attribute="Backslash Code" context="#pop" String="^[\s]*%1;?$" dynamic="true" endRegion="Heredoc" />
         <IncludeRules context="commonheredoc" />
         <IncludeRules context="##HTML" />
       </context>
       <context name="cssheredoc" attribute="Normal Text" lineEndContext="#stay" dynamic="true">
-        <RegExpr attribute="Backslash Code" context="#pop" String="^%1;?$" dynamic="true" endRegion="Heredoc" />
+        <RegExpr attribute="Backslash Code" context="#pop" String="^[\s]*%1;?$" dynamic="true" endRegion="Heredoc" />
         <IncludeRules context="commonheredoc" />
         <IncludeRules context="##CSS" />
       </context>
       <context name="mysqlheredoc" attribute="Normal Text" lineEndContext="#stay" dynamic="true">
-        <RegExpr attribute="Backslash Code" context="#pop" String="^%1;?$" dynamic="true" endRegion="Heredoc" />
+        <RegExpr attribute="Backslash Code" context="#pop" String="^[\s]*%1;?$" dynamic="true" endRegion="Heredoc" />
         <IncludeRules context="commonheredoc" />
         <IncludeRules context="##SQL (MySQL)" />
       </context>
       <context name="javascriptheredoc" attribute="Normal Text" lineEndContext="#stay" dynamic="true">
-        <RegExpr attribute="Backslash Code" context="#pop" String="^%1;?$" dynamic="true" endRegion="Heredoc" />
+        <RegExpr attribute="Backslash Code" context="#pop" String="^[\s]*%1;?$" dynamic="true" endRegion="Heredoc" />
         <IncludeRules context="commonheredoc" />
         <IncludeRules context="Normal##JavaScript" />
       </context>
       <context name="heredoc" attribute="String" lineEndContext="#stay" dynamic="true">
-        <RegExpr attribute="Backslash Code" context="#pop" String="^%1;?$" dynamic="true" endRegion="Heredoc" />
+        <RegExpr attribute="Backslash Code" context="#pop" String="^[\s]*%1;?$" dynamic="true" endRegion="Heredoc" />
         <IncludeRules context="commonheredoc" />
       </context>
       <context name="commonheredoc" attribute="String" lineEndContext="#stay">