fix: support cookie v2.x

[Tony133]

Proposal:

• Updates @fastify/cookie to work with cookie v2.x(v2.0.0: https://github.com/jshttp/cookie/releases/tag/v2.0.0). cookie v2 is a breaking release: it drops the parse(str, opts) and serialize(name, value, opts) exports entirely, replacing them with parseCookie(str, opts) and stringifySetCookie({ name, value, ...opts }, encodeOpts).
  Since index.js still called cookie.parse(...) / cookie.serialize(...), every call became undefined is not a function, causing every route that touches cookies (setting, clearing, or parsing) to respond with a here: 500, see test errors here: https://github.com/fastify/fastify-cookie/actions/runs/28953073061/job/85904705783?pr=356#step:5:763 .
• This PR should resolved this PR: chore: bump cookie from 1.1.1 to 2.0.1 in the dependencies group across 1 directory #356

Change

• Import parseCookie / stringifySetCookie from cookie v2.x and wrap them in local parse(str, opts) / serialize(name, value, opts) helpers that preserve the old 3-argument call shape.
• Route all internal usages (setCookie, clearCookie, request cookie parsing, the serializeCookie/parseCookie decorators, and the module.exports.serialize/.parse aliases) through these wrappers, so the plugin's public API is unchanged.
• Bump cookie to ^2.0.0 in package.json.
• Fix two README links that referenced cookie v1's old anchor names.

[Fdawgs]

A lot of stylistic changes in here?

Likewise I wouldn't class this as a fix, it's just a dependency update isn't it?

[Tony133]

A lot of stylistic changes in here?

Likewise I wouldn't class this as a fix, it's just a dependency update isn't it?

Is a dependency update that required some changes due to the renaming of certain function

[mcollina]

lgtm