[MBL-1712] No Reward Option Not Shown in Edit Reward Flow

[scottkicks]

📲 What

Bug found in QA

• When pledging with a "no reward" selection this option wasn't being shown in the "Edit Reward" flow.
• It also wasn't selectable/editable

🤔 Why

• We should be showing the currently selected reward
• The currently selected reward should be selectable so that backers can update their pledge/bonus amounts. Since those steppers were moved to the rewards screen we need to update this behavior.

🛠 How

Instead of only allowing rewards in the "Edit Rewards" flow to be editable if they have add ons we should update this condition so that it's true if it has add ons and/or the no shipping at checkout feature flag is on.

👀 See

✅ Acceptance criteria

• Backers can select their current pledged reward and adjust their bonus/pledge amounts
• Backers can change rewards/add-ons etc. successfully
• When the feature flag is off, "edit reward" and "manage pledge" flows work as normal

[ifosli]

Nice! I'm surprised this automatically passes existing tests - it'd be nice to add a test to cover this case as part of this pr!