Fix `blob.service_url` for supports string or nil `:filename` option.

- Make sure `blob.service_url` present a `ActiveStorage::Filename` type to `serivce.url`.
- Add `ActiveStorage::Filename.wrap` method.

before:

```rb
blob.service_url(filename: ActiveStorage::Filename.new("new.txt"))

blob.service_url(filename: "new.txt")
=> NoMethodError: undefined method `parameters' for "new.txt":String

params = {}
blob.service_url(filename: params[:filename])
=> NoMethodError: undefined method `parameters' for nil:NilClass
```

after:

```rb
blob.service_url(filename: "new.txt")
blob.service_url(filename: nil)
```

0 files changed, 0 insertions, 0 deletions