Add --context for karmadactl init

[lonelyCZ]

Signed-off-by: lonelyCZ 531187475@qq.com

What type of PR is this?
/kind feature

What this PR does / why we need it:

Which issue(s) this PR fixes:
Fixes #1744

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

`karmadactl`: Introduced `--context` flag to specify the context name to use.

[XiShanYongYe-Chang]

Will these deletions have any impact?

[lonelyCZ]

There should no impacts. They all have default value.

karmada/vendor/k8s.io/client-go/rest/config.go

Lines 115 to 121 in 2d47c5b

	// QPS indicates the maximum QPS to the master from this client.
	// If it's zero, the created RESTClient will use DefaultQPS: 5
	QPS float32
	// Maximum burst for throttle.
	// If it's zero, the created RESTClient will use DefaultBurst: 10.
	Burst int

karmada/vendor/k8s.io/client-go/rest/config.go

Lines 284 to 294 in 2d47c5b

	// AcceptContentTypes specifies the types the client will accept and is optional.
	// If not set, ContentType will be used to define the Accept header
	AcceptContentTypes string
	// ContentType specifies the wire format used to communicate with the server.
	// This value will be set as the Accept header on requests made to the server, and
	// as the default content type on any object sent to the server. If not set,
	// "application/json" is used.
	ContentType string
	// GroupVersion is the API version to talk to. Must be provided when initializing
	// a RESTClient directly. When initializing a Client, will be set with the default
	// code version.

[XiShanYongYe-Chang]

got it.

[RainbowMango]

What's the reason why we set them explicitly? @prodanlabs

[RainbowMango]

Generally looks good to me. Please @prodanlabs take a look.
(I updated the release notes to the PR description)

[RainbowMango]

/lgtm
/approve

[karmada-bot]

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