Default Theme - External Link Regex: Allow for System Deep Links

[DBULL7]

Summary

Allow users to have links that open system applications (i.e. deep links).

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

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

If changing the UI of default theme, please provide the before/after screenshot:

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:

• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)

You have tested in the following browsers: (Providing a detailed version will be better.)

• Chrome
• Firefox
• Safari
• Edge
• IE

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

• A convincing reason for adding this feature
• Related documents have been updated
• Related tests have been updated

To avoid wasting your time, it's best to open a feature request issue first and wait for approval before working on it.

Other information:

My company is using Vuepress for an internal documentation site. We would like to be able to use deep links to open our bug tracking app so other internal teams can help improve our documentation (most employee's won't have access to the enterprise Github and the repo is restricted). The current default-theme external link regex doesn't take into account these types of links for navbar links or for editLinks with our deep link in place of a normal docRepo link in themeConfig and fails to open them correctly (unless done manually with in markdown <a> tags inside the pages themselves). I found the Apple documentation here that best describes what we're trying to do. If you have any questions please reach out and hopefully I can answer them!

We're huge fans of what y'all do! Thank you for your time and consideration 👋

[ulivz]

Cool! Thanks for your support for VuePress!

[vue-bot]

Thanks again! 💚

[xr0master]

Only one question guys, why 4? sms, ftp and etc... going to fork