[Improvement] support offline KubeBlocks upgrades

[jelipo]

Problem

kbcli kubeblocks upgrade currently resolves the KubeBlocks chart from the public Helm repository and downloads CRDs from GitHub or JihuLab.

Offline and private deployments already package the matching chart and CRD files in their installer image, but kbcli cannot use these artifacts while preserving its native upgrade sequence.

Proposed solution

Add optional local artifact flags to kbcli kubeblocks upgrade:

• --chart-file for a packaged KubeBlocks Helm chart
• --crds-file for a packaged KubeBlocks CRD manifest

When a local chart is provided, skip the public chart version lookup and Helm repository update. When a local CRD file is provided, read it through the existing CRD reconciliation flow. Keep the existing online behavior when these flags are omitted.

Acceptance criteria

• KubeBlocks can be upgraded with local chart and CRD files without public repository access.
• The existing add-on preservation, CRD reconciliation, conversion, Helm value reuse, and readiness waits remain unchanged.
• Online upgrades continue to work when no local files are specified.