tests/cmdline: Improve repl.c autocomplete test coverage.

tests/cmdline/repl_autocomplete.py

+# tests for autocompletion
+impo	sys
+not_exist.	
+not_exist	
+x = '123'
+1, x.isdi	()
+i = str
+i.lowe	('ABC')
+j = None
+j.	

tests/cmdline/repl_autocomplete.py.exp

+MicroPython \.\+ version
+Use \.\+
+>>> # tests for autocompletion
+>>> import sys
+>>> not_exist.
+>>> not_exist
+>>> x = '123'
+>>> 1, x.isdigit()
+(1, True)
+>>> i = str
+>>> i.lower('ABC')
+'abc'
+>>> j = None
+>>> j.
+>>>