Add --wait flag to databases migrate command

[loosla]

What is the problem this feature would solve? Please describe.
doctl aims to be useful in scripting. One way it does this is by providing a --wait flag for long running, async operations to block until they are complete rather than making the user implement polling in their own script. Some examples include:

• doctl database create --wait
• doctl compute droplet create --wait
• doctl kubernetes cluster create --wait
• doctl apps create --wait

Currently the doctl databases migrate command does not have a --wait flag.

Describe the solution you'd like
Add a --wait flag to the doctl databases migrate command. It should poll the /v2/databases/$DATABASE_ID/migrate, blocking until the database cluster's status attribute moves from migrating to online.

Additional context
Following the code path starting here demonstrates how doctl database create's --wait flag is implemented:

doctl/commands/apps.go

Line 282 in de1918a

if wait {

[shashank-priyadarshi]

@loosla can I please take this up?

[loosla]

@shashank-priyadarshi We would certainly value your input. 👍

[SkySingh04]

This looks like a fun issue, Will be working on this!

[shashank-priyadarshi]

@SkySingh04 it will possibly be duplicate effort as I have already started work on this.
@loosla can you please mark this issue as assigned?

[loosla]

I appreciate everyone's interest in contributing! Just a friendly reminder: when we assign someone to a PR in an open repository, it can sometimes limit opportunities for other developers to contribute, it may lead to issues being abandoned and work not progressing.

We generally would like to follow a first-come, first-served approach for assignments to ensure fairness.

I recommend leaving a comment to let others know you've started working on this issue and link your PR, along with an approximate timeline for when you expect to finish. This way, everyone will be aware that you're handling it.

Thank you for your understanding! 🌊 🐬 🌊

[SkySingh04]

Thank you for the clarification @loosla , Do you recommend I work on this issue or can you point me towards any other CLI issue I can work towards? I have worked extensively on the Keploy CLI tool before.

[shashank-priyadarshi]

I recommend leaving a comment to let others know you've started working on this issue and link your PR, along with an approximate timeline for when you expect to finish. This way, everyone will be aware that you're handling it.

Sure thanks @loosla .
I have indeed started work on this in the past week, and looking to close this by Mon.

[SkySingh04]

Hey @loosla , Since the deadline for this was Monday and no PR was raised, I have raised a PR for this issue!