Fix parse cookie

[huadong]

当cookie的key=value不是第一项时候，存在bug。比如：cookie: 'max-age=1; ooo=hhh'。
同时对于value值，调用decodeURIComponent进行解码。

[JuneAndGreen]

document.cookie 设置时，会将第一项识别为 key=value，比如 document.cookie = 'max-age=1; ooo=hhh'，浏览器会将 max-age 识别为 key ，所以此处使用第一项作为 key-value 对，主要是为了对齐浏览器的这个特性。

[huadong]

对齐浏览器其实没啥问题，Axios也是这么识别的。
主要是企鹅的API老出bug。有时候一些版本会出现第一项不是key=value。

[huadong]

从规范来说，你是对的，把第一个cookie-pair看作key-value。

COOKIE RFC

4.1.1. Syntax

Informally, the Set-Cookie response header contains the header name
"Set-Cookie" followed by a ":" and a cookie. Each cookie begins with
a name-value-pair, followed by zero or more attribute-value pairs.
Servers SHOULD NOT send Set-Cookie headers that fail to conform to
the following grammar:

set-cookie-header = "Set-Cookie:" SP set-cookie-string
set-cookie-string = cookie-pair *( ";" SP cookie-av )
cookie-pair = cookie-name "=" cookie-value
cookie-name = token
cookie-value = *cookie-octet / ( DQUOTE *cookie-octet DQUOTE )
cookie-octet = %x21 / %x23-2B / %x2D-3A / %x3C-5B / %x5D-7E
; US-ASCII characters excluding CTLs,
; whitespace DQUOTE, comma, semicolon,
; and backslash
token = <token, defined in [RFC2616], Section 2.2>

cookie-av = expires-av / max-age-av / domain-av /
path-av / secure-av / httponly-av /
extension-av
expires-av = "Expires=" sane-cookie-date
sane-cookie-date = <rfc1123-date, defined in [RFC2616], Section 3.3.1>
max-age-av = "Max-Age=" non-zero-digit *DIGIT
; In practice, both expires-av and max-age-av
; are limited to dates representable by the
; user agent.
non-zero-digit = %x31-39
; digits 1 through 9
domain-av = "Domain=" domain-value
domain-value =
; defined in [RFC1034], Section 3.5, as
; enhanced by [RFC1123], Section 2.1
path-av = "Path=" path-value
path-value = <any CHAR except CTLs or ";">
secure-av = "Secure"
httponly-av = "HttpOnly"
extension-av = <any CHAR except CTLs or ";">