[feat][workflow] add dead link checker to CI/CD

^{Originally posted by **Anonymitaet** January 6, 2023}
# Issue

Sometimes 404 errors occur in docs.

Currently, we use the following ways to check them:

### Method 1: use tools to check them manually at regular intervals

- [Dr. Link Checker](https://www.drlinkcheck.com/)

- [W3C Link Checker](https://validator.w3.org/checklink?uri=http%3A%2F%2Fpulsar.apache.org%2Fdocs&hide_type=all&recursive=on&depth=4&check=Check)

- [Dead Link Checker](https://www.deadlinkchecker.com/)

#### Disadvantages

- It's easy to forget to do this task.

- It entirely depends on the contributor's willingness.

### Method 2: check the links through the local preview process

It reminds you of 404 errors if any.

#### Disadvantages

- Some contributors need to preview docs on the local machines and the link check step is skipped.

- Even though contributors preview docs and get reminders of 404 issues, they can ignore this error and still submit doc PRs.

# Solution

Can we implement a `dead link check` to the CI/CD process in `pulsar-site`?

### Example

Skywalking

### Benefits

- Docs submitted from all contributors can be checked in a prominent and easy way

- If we want to ensure no 404 links in docs, we can set this check as `required`. In this way, PRs can not be merged with 404 issues.

- (Other doc-related checks, e.g., **grammar checks, typo checks**, etc can also be implemented)

cc @momo-jun @DaveDuggins @D-2-Ed