Display both consent messages to new flutter users for legacy analytics + package:unified_analytics #124605

We want to ensure that the messages for both the legacy and new unified analytics packages are both being shown per the privacy document.

Case 1: New Flutter developer who has never seen either consent messages

We want to show both of the messages and then follow up with a short explanation of why they are seeing two different consent messages

Case 2: Flutter developer who has already seen the legacy consent message

Because they have already seen the legacy consent message, we don't need to show it to them again. However, because package:uniifed_analytics is a new addition to flutter-tools, we have to show the new consent message. If they choose to opt out of analytics collection here, they can run either flutter --disable-telemetry or flutter config --no-analytics. Both will result in the same outcome; they will be opted out of both analytics collection systems

Case 3: Flutter developer who has already seen the legacy consent message AND opted out previously

We will still need to show the consent message for the new analytics package while also informing them that we understand that they have opted out previously and that we will continue to opt them out of the new analytics package