Promote sources in mime/multipart package

These were contributed by @am0o0 in
#13553 .

Author: owen-mc

go/ql/lib/ext/mime.multipart.model.yml

@@ -1,3 +1,12 @@
+extensions:
+  - addsTo:
+      pack: codeql/go-all
+      extensible: sourceModel
+    data:
+      - ["mime/multipart", "FileHeader", True, "Open", "", "", "ReturnValue[0]", "remote", "manual"]
+      - ["mime/multipart", "FileHeader", True, "FileName", "", "", "", "remote", "manual"]
+      - ["mime/multipart", "FileHeader", True, "Header", "", "", "", "remote", "manual"]
+      - ["mime/multipart", "Form", True, "Value", "", "", "", "remote", "manual"]
 extensions:
   - addsTo:
       pack: codeql/go-all

go/ql/src/experimental/frameworks/DecompressionBombs.qll

@@ -4,23 +4,6 @@
 
 import go
 
-class MimeMultipartFileHeader extends UntrustedFlowSource::Range {
-  MimeMultipartFileHeader() {
-    exists(DataFlow::FieldReadNode frn | this = frn |
-      frn.getField().hasQualifiedName("mime/multipart", "FileHeader", ["Filename", "Header"])
-    )
-    or
-    exists(DataFlow::Method m |
-      m.hasQualifiedName("mime/multipart", "FileHeader", "Open") and
-      this = m.getACall().getResult(0)
-    )
-    or
-    exists(DataFlow::FieldReadNode frn |
-      frn.getField().hasQualifiedName("mime/multipart", "Form", "Value")
-    )
-  }
-}
-
 /** Provides a taint tracking configuration for reasoning about decompression bomb vulnerabilities. */
 module DecompressionBomb {
   import experimental.frameworks.DecompressionBombsCustomizations