Allow adding multiple filters

I need to use multiple filters. While I can easily implement a function to do this and provide it as a single filter, it would be nice to have the option to add filters independently, especially when dynamically building the list of `ProgramOption`.

An example:

```go
p := tea.NewProgram(
    MyModel{},
    tea.WithAddedFilter(AlterSomeEvent),
    tea.WithAddedFilter(RemoveSomeOtherEvent))
```
