Use subnet package in pkg for license validation

[anjalshireesh]

Community Contribution License

All community contributions in this pull request are licensed to the project maintainers
under the terms of the [Apache 2 license] (https://www.apache.org/licenses/LICENSE-2.0).
By creating this pull request I represent that I have the right to license the
contributions to the project maintainers under the Apache 2 license.

Description

Most of the code related to license validation is now available in
minio/pkg. So remove it from mc and use the function(s) from pkg.

Motivation and Context

Code reuse

How to test this PR?

Test following commands:

• mc license register
• mc license update
• mc support diag
• mc support perf

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Optimization (provides speedup with no functional changes)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• Fixes a regression (If yes, please add commit-id or PR # here)
• Unit tests added/updated
• Internal documentation updated
• Create a documentation update request here

[shtripat]

LGTM. Verified.