LibELF+LibCoreDump: Add a ProcessInfo notes entry

This is a new NotesEntry type which contains information related to the
coredump's process:

- PID
- executable path

Having these in the coredump explicitly avoids having to parse them from
the coredump filename and backtrace, respectively.

Libraries/LibELF/CoreDump.h

@@ -36,6 +36,7 @@ struct [[gnu::packed]] NotesEntryHeader
 {
     enum Type : u8 {
         Null = 0, // Terminates segment
+        ProcessInfo,
         ThreadInfo,
         MemoryRegionInfo,
     };
@@ -48,6 +49,13 @@ struct [[gnu::packed]] NotesEntry
     char data[];
 };
 
+struct [[gnu::packed]] ProcessInfo
+{
+    NotesEntryHeader header;
+    int pid;
+    char executable_path[]; // Null terminated
+};
+
 struct [[gnu::packed]] ThreadInfo
 {
     NotesEntryHeader header;