epic: Basic Syncer version skew checks and reporting

[davidfestal]

TL;DR

Ensure that incompatible syncer installations are correctly detected, managed and reported.

Progress tracking #

EPIC detailed issues and overall progress can be tracked with the following project view

Demo Objective

• The syncer running should check that its kcp version corresponds to, or is compatible with, the kcp version of the CLI kcp workload sync command that the user used to create, or most recently update, the corresponding SyncTarget
• The Syncer virtual workspace should check that the kcp version of the syncer that accesses it corresponds to, or is compatible with, its own kcp version.
• Any version discrepancy, along with its criticity (warning or error) should be reported in the SyncTarget, so thatr the end user would be aware of it.
• Any critical version discrepancy (related with incompatible changes) should prevent the Syncer to start, or syncing of resources to happen.

Demo Steps

No response

Action Items

• Scope of the current demo is necessary to fit in the prototype boundaries

Stories

• kcp-dev/kcp#2351
• Cleanup / harmonize the client user-agents in the Syncer code #65
• Syncer virtual workspace should extract the syncer kcp version from the user agent and validate it is compatible. #81

[ncdc]

/milestone clear

[mjudeikis]

/transfer-issue contrib-tmc