migrate to using cf api v3 only

[metskem]

Is your feature request related to a problem? Please describe.
The cf api v2 is deprecated for quite some time, and more concrete steps have been taken to completely remove it:

• https://github.com/cloudfoundry/community/blob/main/toc/rfc/rfc-0032-cfapiv2-eol.md
• [RFC0032] CF API v2 End of Life cloudfoundry/community#1001

Describe the solution you'd like
Replace the use of cf api v2 with cf api v3.

Describe alternatives you've considered
I don't see alternatives.

Additional context
We ran one of our foundations with the cf api v2 disabled to see which things would break, and cf-mgmt was one of them:

2024/12/11 10:45:57 E1211 10:45:57.899322 20 initialize.go:132] Error obtaining a New CF Client: Could not get api /v2/info: invalid character 'V' looking for beginning of value
error: Could not get api /v2/info: invalid character 'V' looking for beginning of value

[metskem]

O BTW, I asked the question last week on the cf-mgmt slack channel, but there isn't much activity there.