Switches the order of initialization in the OAuth flow within
the NewOAuthFlow method. Instead of initializing the
Device Authorization Flow first, it now initializes
the PKCE Authorization Flow first, and falls back
to the Device Authorization Flow if the PKCE initialization fails.
Enhance the user experience by enabling authentication to Netbird using Single Sign-On (SSO) with any Identity Provider (IDP) provider. Current client offers this capability through the Device Authorization Flow, however, is not widely supported by many IDPs, and even some that do support it do not provide a complete verification URL.
To address these challenges, this pull request enable Authorization Code Flow with Proof Key for Code Exchange (PKCE) for client logins, which is a more widely adopted and secure approach to facilitate SSO with various IDP providers.
