[Forwardport] Trim username on customer account login page

[vijay-wagento]

Original Pull Request

magento#15365

Trim email address on customer account login page generally when copy and paste.

Description

Trim email address by remove leading or trailing space on the customer account login page email field.

Fixed Issues (if relevant)

1. IE11 user login email validation fails if field has leading or trailing space magento/magento2#6058: IE11 user login email validation fails if field has leading or trailing space

Manual testing scenarios

1. Open customer account login page in Firefox or IE browser.
2. Try to add space before entering an email address in the Email field.
3. Copy " johndoe@domain.com " and paste in the Email field. It will automatically remove leading or trailing space.

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)