Make all SnapshotTestOptions configurable via DSL

[skuzzle]

We should enhance the DSL so that all the options that can be configured via @SnapshotTestOptions can also be configured via the DSL like

@Test
void someTest(Snapshot snapshot) {
    snapshot.withOptions(options -> options
        .withtextDiffContextLines(10)
        .withalwaysPersistActualResult(true))
    ...
}

This solution is kind of in conflict with the current SnapshotConfiguration class approach which serves partly the same use case but isn't configurable from public API.

Solving this might require deeper refactorings in the core module