add syntax highlight for *.kdu component files

[khanhduy1407]

This PR adds detection and highlighting for Kdu.js components with the *.kdu extension, using kdu-syntax-highlight.

Checklist:

• I am associating a language with a new file extension.
  • The new extension is used in hundreds of repositories on GitHub.com
    • Search results for each extension:
      • https://github.com/search?utf8=%E2%9C%93&type=Code&ref=searchresults&q=extension%3Akdu+NOT+xml
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • arrow.kdu
      • basic.kdu
      • langs.kdu
    • Sample license(s):
      • MIT
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

[lildude]

There are only 207 .kdu files with most of these owned by only 2 users/orgs. This is no where near meeting our documented requirements or even the temporarily relaxed requirements so I'm closing this PR. Please feel free to create a new one when popularity meets our requirements in future.