agent-toolkit-for-aws: we dont have default setup to configure agent toolkit for mutiple aws account (scenario of Management and OU account)

### Describe the feature

while following the documentation to setup the toolkit, it asked me to setup a default aws account, well that is nice and handy. But what are we suppose to do when we have more than 40 OU accounts under a Management account and how do we make use of toolkit to switch between them? default is working fine as expected but do we have to do customize manually everytime we want to perform anything in diffrent account?

### Use Case

switching between diffrent acconts based on profiles to manage them quickly

### Proposed Solution

if there was a hot key or way we can switch between the desired account it would be a pretty handy tool , i dont have concrete solution but if we could figure out to switch between profiles that would be better.

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

Start with the toolkit setup documentation and trace the existing default-account and profile-handling entry points. Define the supported Management-account and OU-account workflow, then verify that a user can switch between configured accounts without manually reconfiguring the toolkit each time.

Written by the indexing model from the issue text.