ohos: Implement cookie management

Implement QOhosWebViewPrivate::setCookie(), deleteCookie() and
deleteAllCookies(), which were previously empty stubs. The work is
delegated to the controller, which drives ArkWeb's static
WebCookieManager through QNapi.

setCookie() sets a "name=value" cookie with configCookieSync() and
emits cookieAdded() on success. WebCookieManager is URL-based, so the
domain is converted into an https:// URL with any leading dot
stripped. configCookieSync() returns void, so deleteCookie() first
queries the store with fetchCookieSync() and only expires the cookie
(Max-Age=0) and emits cookieRemoved() when it actually exists;
deleting an unknown name or domain is a no-op. No client-side
registry is kept, so the emitted signals stay consistent with the
shared cookie store.

deleteAllCookies() reads the whole store with fetchAllCookies()
(@since 23), clears it with clearAllCookiesSync() and emits
cookieRemoved() for each removed cookie. Querying the live store
keeps the notifications correct without tracking cookies client-side.

Task-number: QTBUG-146838
Pick-to: 6.12
Change-Id: I6bf99d97844fec64a4104f8a634843e58de6500a
Reviewed-by: Zbigniew Chyla <zbigniew.chyla@qt.io>
Reviewed-by: Liang Qi <liang.qi@qt.io>