test-tables: ellide boring parts of sparse mappings

test: use assert_se() when testing tables so that we get a useful error when something fails

test-tables: add new entries One missing string found. A few things had to be moved around to make it possible to test them.

test-tables: allow sparse tables and check mapping for -1 Jan: test-tables fails on my system. The one it's failing on is: syscall: 222 → (null) → -1 ... and indeed, our own tables should not have holes, but syscall tables certainly might.

test: add trivial test for syscall table and extend table tests to error paths

tests: add tests for string lookup tables The tests check if the tables have entries for all values in the enum, and that the entries are unique.