[lldb][NFC] Add more test for builtin formats

Reland 90c1af10 . This changes the char format
tests which were printing the pointer value of the C-string instead of its
contents, so this test failed on other machines. Now they just print the
bytes in a uint128_t.

Original commit description:

The previous tests apparently missed a few code branches in DumpDataExtractor
code. Also renames the 'test_instruction' which had the same name as another
test (and Python therefore ignored the test entirely).