mirror: let user decide whether to skip errors if client runs in watch / active-active mode

[mchtech]

Description

Fix #4883

Motivation and Context

When client has run with --watch and minio servers are down (or encounter a network error), watch request and mirroring progress will not recover forever after serveral retries.

In version 2022-04-01, mirroring progress will be cancelled and restarted when statusCh returns a no-ignored error.

After PR 4032, mirroring progress will not be restarted forever when client runs with --watch and/or --active-active.

This patch restores the "restart" policy in version 2022-04-01 and users can also pass --skip-errors to keep same behavior of current implementation.

How to test this PR?

• mc mirror --watch --remove --overwrite --debug --summary [alias]/[bucket]/path/ ./
• use iptables to drop packages from minio servers
• restore iptables after some minutes
• client resumes to work

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