fix: support 'mc put --if-not-exists'

[harshavardhana]

Community Contribution License

All community contributions in this pull request are licensed to the project maintainers
under the terms of the Apache 2 license.
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

fix: support 'mc put --if-not-exists'

Also allow 'mc get --version-id'

Motivation and Context

Just nice to have flags that have helped me
to test things locally.

How to test this PR?

As mentioned in the PR

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

[harshavardhana]

if-not-exists flag is currently hidden, until we decide to take full inputs like --if-none-match

[jiuker]

Please fix the lint or add //nolint at that line.

[zveinn]

LGTM, just remove the unused var.

[klauspost]

(yeah, or use it if it is supposed to be used)