Add support for Java Template Engine

[maths22]

Description

This template adds support for JTE. I expect this PR to immediate go into "Pending Popularity", but since I already prepared this PR before running the search, I might as well submit it so it is out there and if JTE ever actually gets popular enough it will be ready :)

Checklist:

• I am adding a new language.
  • The extension of the new language is used in hundreds of repositories on GitHub.com.
    • Search results for each extension:
      • jte: https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.jte+%28%40param+OR+%40import%29
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • Originally taken from a private repo
    • Sample license:
      • Linguist MIT license (This was originally authored by me, and I hereby license it to linguist under the MIT license)
  • I have included a syntax highlighting grammar: https://github.com/maj2c/jte-template-syntax-highlight
  • I have added a color
    • Hex value: #2A6277
    • Rationale: Selected to match other java-related languages (e.g. JSP and Java Properties)
  • [n/a] I have updated the heuristics to distinguish my language from others using the same extension.

[lildude]

I expect this PR to immediate go into "Pending Popularity"

Yeup 😁 … only 350 files with that extension so it's likely to be a while before this is merged, but I'll check each time I make a release.