Description

Add Go template as a new language.
This PR is intended to solve #7639 and #6196 so that Helm chart repositories are classified correctly.
Note that Go template use braces similarly to Jinja {{ }} and the file extension might not differentiate template languages in general. So this PR focus only on Smarty - Go template differences as they usually share the same extension in Helm charts.

Rationale for added extensions:

• .gohtml: IntelliJ IDEA has association with this extension. (link to source)
• .html.tmpl: GitHub search verifies that is widely used. Mentioned in a StackOverflow answer and also default in a Prettier plugin.
• .gotmpl, .tmpl: Default extensions of Go template files the Go language server (gopls) (link to documentation). Also the VS Code Go Plugin use this default (link to docs).
• .tpl: Convention used in Helm charts as stated by the Helm documentation ("Conventionally, Helm charts put [...] templates inside of a partials file, usually _helpers.tpl")

Since none of the extensions are defined by the Go template documentation, and none of the supporting tools stick to one particular default, I left the list in alphabetical order in the languages.yml config.

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:
      • _helpers.tpl https://github.com/search?type=code&q=NOT+is%3Afork+path%3A**%2F_helpers.tpl+%7B%7B-
      • .gohtml https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.gohtml
      • .gotmpl https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.gotmpl
      • .html.tmpl https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.html.tmpl
      • .tmpl https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.tmpl+%7B%7B-
      • .tpl https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.tpl+%7B%7B-
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • _helpers.tpl source
      • base.tpl source
      • batch.gohtml source
      • _templates.gotmpl source
      • crd.tmpl source
      • letter.tmpl source
      • prettier.html.tmpl source
    • Sample license(s):
      • _helpers.tpl CC BY 4.0
      • base.tpl MIT
      • batch.gohtml MIT
      • _templates.gotmpl Apache License 2.0
      • crd.tmpl Apache License 2.0
      • letter.tmpl BSD-3-Clause
      • prettier.html.tmpl MIT License
  • I have included a syntax highlighting grammar: https://github.com/jinliming2/vscode-go-template
  • I have added a color
    • Hex value: #00ADD8
    • Rationale: Used same color as all other Go languages
  • I have updated the heuristics to distinguish my language from others using the same extension.

• I am fixing a misclassified language

  • I have included a new sample for the misclassified language:
    • Sample source(s):
      • header.tpl source
      • index.tpl source
    • Sample license(s):
      • header.tpl LGPL LICENSE
      • index.tpl LGPL LICENSE
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

• I am updating a grammar submodule