cookie & privacy consent blocklet

[mave99a]

a blocklet to deal with privacy policy and cookie consent to meet legal requirements.

reference:

• https://github.com/ArcBlock/ux/issues/668
• https://termly.io/
• https://mp.weixin.qq.com/s/JnhnMhb0PrJ4t_liFxsASQ
• https://www.kaamel.com/en/