fix(compiler): support decode   in the value of prop and attribute

[JuniorTour]

Fix #8895.

After this commit, the   value of attribute and props will be decoded into ' ', like the other HTML entities.

Demo

Before Fix:

• https://codepen.io/avertes/pen/LYYpNRe
• https://jsfiddle.net/50wL7mdz/756973/

After Fix:

• attribute value: https://jsfiddle.net/juniortour/nv041crt/
• prop value: https://jsfiddle.net/juniortour/tcgv03fa/13/

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• It's submitted to the dev branch for v2.x (or to a previous version branch), not the master branch
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• All tests are passing: https://github.com/vuejs/vue/blob/dev/.github/CONTRIBUTING.md#development-setup
• New/updated tests are included

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information: