tests(f2/repl): migrate debugger tests

Change-Id: I2cc1d45db2e5e0b8cea6798c70e13ede57fea6ee

tests/functional2/repl_characterization/debugger/no_nested_debugger.md

@@ -0,0 +1,70 @@
+---
+args: ['--debugger', '-f', 'no_nested_debuggers.nix']
+files: ['no_nested_debuggers.nix']
+---
+
+```output
+Lix VERSION
+Type :? for help.
+info: breakpoint reached
+
+```
+we enter a debugger via builtins.break in the input file.
+
+```nix
+"values show"
+```
+```output
+"values show"
+
+```
+
+
+causing another debugger even should not nest, but simply print the error, skip the breakpoint, etc as appropriate
+
+```nix
+builtins.break 2
+builtins.throw "foo"
+assert false; 2
+```
+```output
+2
+
+error:
+       … caused by explicit throw
+         at «string»:1:1:
+            1| builtins.throw "foo"
+             | ^
+
+       error: foo
+
+error: assertion failed
+       at «string»:1:1:
+            1| assert false; 2
+             | ^
+
+```
+
+
+exiting the debugger frame should allow another to open.
+
+```nix
+:c
+builtins.throw "bar"
+```
+```output
+Loading installable ''...
+error: bar
+
+```
+
+
+and once again, more breakpoints are ignored.
+
+```nix
+builtins.break 3
+```
+```output
+3
+
+```