tests/cmdline/repl_inspect: Add new test for -i option.

This adds a new test to verify that the inspect (-i) command line option
works.

tests/cmdline/repl_inspect.py

@@ -0,0 +1,2 @@
+# cmdline: -c print("test") -i
+# -c option combined with -i option results in REPL

tests/cmdline/repl_inspect.py.exp

@@ -0,0 +1,6 @@
+test
+MicroPython \.\+ version
+Use \.\+
+>>> # cmdline: -c print("test") -i
+>>> # -c option combined with -i option results in REPL
+>>>