Testsuite: added compile error testcases and discovered one new issue.

TODO

src/lib-sieve/ext-encoded-character.c

src/testsuite/tests/compile/errors.svtest

src/testsuite/tests/compile/errors/address-part.sieve

src/testsuite/tests/compile/errors/encoded-character.sieve

src/testsuite/tests/compile/errors/envelope.sieve

src/testsuite/tests/compile/errors/keep.sieve

src/testsuite/tests/compile/errors/size.sieve

src/testsuite/tests/compile/errors/stop.sieve

src/testsuite/tests/control-structures.svtest