feature(ghidra): use configurable code prefix marker for line indicator

As the source code and the decompiled sources are essentially the same
thing, lets just reuse the existing code prefix marker to indicate the
current line instead of using a hardcoded plain string.

A comment compatible marker is used before the syntax highlighter to
avoid any highlight and parsing confusion which is later replaced by the
colorized variant of the prefix marker before returning the results.

Furthermore we only replace the amount of indented spaces that is
required to fill the space for the code prefix marker.

pwndbg/ghidra.py

@@ -2,6 +2,7 @@ import os
 
 import gdb
 
+import pwndbg.color.context as C
 import pwndbg.color.syntax_highlight as H
 import pwndbg.radare2
 import pwndbg.regs
@@ -51,12 +52,14 @@ def decompile(func=None):
         if pos_annotations:
             curline = source.count("\n", 0, pos_annotations[0]["start"])
     source = source.split("\n")
-    # Append --> for the current line if possible
+
+    # Append code prefix marker for the current line and replace it later
+    current_line_marker = '/*%%PWNDBG_CODE_MARKER%%*/'
     if curline is not None:
         line = source[curline]
         if line.startswith('    '):
-            line = line[4:]
-        source[curline] = '--> ' + line
+            line = line[min(4, len(pwndbg.config.code_prefix) + 1):]
+        source[curline] = current_line_marker + ' ' + line
     # Join the source for highlighting
     source = "\n".join(source)
     if pwndbg.config.syntax_highlight:
@@ -66,5 +69,8 @@ def decompile(func=None):
         except: # if non, take the original filename and maybe append .c (just assuming is was c)
             src_filename = filename+".c" if os.path.basename(filename).find(".") < 0 else filename
         source = H.syntax_highlight(source, src_filename)
+
+    # Replace code prefix marker after syntax highlighting
+    source = source.replace(current_line_marker, C.prefix(pwndbg.config.code_prefix), 1)
     source = source.split("\n")
     return source