feat: Add Partitioned Parameter to SetCookie

[Haswf]

What type of PR is this?

feat

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• This PR title match the format: <type>(optional scope): <description>
• The description of this PR title is user-oriented and clear enough for others to understand.
• Attach the PR updating the user documentation if the current PR requires user awareness at the usage level. User docs repo

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feat: SetCookie 增加 Partitioned 参数

(Optional) More detailed description for this PR(en: English/zh: Chinese).

en:
As discuessed, this PR adds partitioned parameter to (*RequestContext).SetCookie, simplifying the use of partitioned cookies.

zh(optional):

(Optional) Which issue(s) this PR fixes:

(Optional) The PR that updates user documentation:

Yes, see cloudwego/cloudwego.github.io#929 for related doc changes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (0d25abe) 82.49% compared to head (3f1e84f) 82.55%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1048      +/-   ##
===========================================
+ Coverage    82.49%   82.55%   +0.05%     
===========================================
  Files           98       98              
  Lines        10025    10030       +5     
===========================================
+ Hits          8270     8280      +10     
+ Misses        1258     1254       -4     
+ Partials       497      496       -1     

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[welkeyever]

LGTM, thx~