fix(amazonq): handle existing Flare connection when migrating SSO connections

[opieter-aws]

Problem

Auth migration to LSP is not handled gracefully when a user downgrades and upgrades to auth on LSP multiple times, causing users to be logged out if they upgrade a second time

Solution

In the auth migration script, call the LSP identity server to check if a token is available. If the token is available, don't migrate the auth connection. If no token is available, migrate.

Added unit tests for the case.

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[github-actions]

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[opieter-aws]

/retryBuilds