Changes that function as a post-commit review of Julien's previous change.

compiler/add_clause.m:
compiler/det_report.m:
compiler/mode_errors.m:
compiler/modes.m:
    Use the sym_name_and_arity format component where appropriate.

compiler/term_constr_errors.m:
    Fix whitespace.

tests/invalid/invalid_main.err_exp:
    Conform to the above.