[LL FIR] rework FirDesignation collector

The main change – now we collect not only `FirRegularClass`, but also
`FirScript`.
This allows us to have a proper context collector for
diagnostics for scripts.
Also, this change fixes dangling files for scripts in `IGNORE_SELF`
as now we have the correct patcher for this case, so we won't resolve
the copied script

^KT-65345
^KT-62841 Fixed

analysis/low-level-api-fir/testData/contextCollector/scripts/insideClassBody.copy.txt

@@ -14,7 +14,7 @@ Tower Data Context:
     Element 6
         Scope: FirScriptDeclarationsScope
             Classifiers:
-                FirRegularClassSymbol public final? class Foo : R|kotlin/Any|
+                FirRegularClassSymbol public final class Foo : R|kotlin/Any|
     Element 7
         Scope: FirLocalScope
             Classifiers:
@@ -27,7 +27,7 @@ Tower Data Context:
             SCRIPT: <script-insideClassBody.kts>
                 lval args: R|kotlin/Array<kotlin/String>|
 
-                public final? class Foo : R|kotlin/Any|
+                public final class Foo : R|kotlin/Any|
                 Type: kotlin.script.templates.standard.ScriptTemplateWithArgs
                 Label: <script>
     Element 9
@@ -38,8 +38,8 @@ Tower Data Context:
         Scope: FirLocalScope
 
 FILE: [ResolvedTo(IMPORTS)] insideClassBody.kts
-    context(<script>@R|kotlin/script/templates/standard/ScriptTemplateWithArgs|)
-    SCRIPT: [ResolvedTo(TYPES)] <script-insideClassBody.kts>
+    context(<script>@kotlin.script.templates.standard.ScriptTemplateWithArgs)
+    SCRIPT: [ResolvedTo(RAW_FIR)] <script-insideClassBody.kts>
         [ResolvedTo(RAW_FIR)] lval args: R|kotlin/Array<kotlin/String>|
 
         public final? [ResolvedTo(RAW_FIR)] class Foo : R|kotlin/Any| {