Fix refresh token issue when using password flow

[GalMunGral]

• Related: ncsa/idot-pma#173
• POST /login and POST /auth/login have the exact same logic. @longshuicy suggested deprecating the POST /login endpoint.
• Applied the same logic for refresh tokens as used in the authorization code flow (GET /auth) so that access tokens obtained through the password flow (POST /auth/login) can also be refreshed by GET /auth/refresh_token.

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[longshuicy]

Code looks good and tested.
One thing I noticed is the "deprecated" not seems to work? I can still POST to the /api/v2/login endpoint with no issue. And i didn't see any notification either.
Could you look into that? if it's not straightforward, maybe we can just delete this endpoint. But we might be careful, a quick search I found there are some scripts (in the scripts folder) still uses this endpoint.

[longshuicy]

After we discussed, could you try below: @GalMunGral

1. Make a utility function of that tokenDB logic. You can put it in backend/app/routers/utils.py.
2. Then revert the deprecate. We might want to keep both endpoints. (so you don't need to worry about making deprecating work)
3. Put the logic in /auth/login and /login

@max-zilla if I've missed anything, please chime in.

[GalMunGral]

After we discussed, could you try below: @GalMunGral

1. Make a utility function of that tokenDB logic. You can put it in backend/app/routers/utils.py.
2. Then revert the deprecate. We might want to keep both endpoints. (so you don't need to worry about making deprecating work)
3. Put the logic in /auth/login and /login

@max-zilla if I've missed anything, please chime in.

Will do!

[max-zilla]

@longshuicy i will take a look at this also but it's ready for another look, thanks.

[longshuicy]

Code looks good and functionality works. Approve.