Add password strength meter and validation on the change password page

As raised by @megoth in https://github.com/solid/node-solid-server/pull/842

Not directly related, but more of a note to self: We've added repeat password on another page, we probably should do that here as well.

But for this case, we need to find a good markup of the password component. I've used two divs with col-md-3in the previous design, so might revert something a bit here, unless you have a better suggestion?

Originally posted by @megoth in https://github.com/solid/node-solid-server/pull/842

先檢視 pull request 842 中的討論，並找到其中提及的 change-password 頁面。在該頁面加入密碼強度計與驗證功能，包括討論中建議的重複密碼行為；完成的標準是頁面能以可見方式衡量強度，並拒絕無效或不相符的密碼。