Variable expansion in repository templates (#9163)

Variable expansion in repository templates (#9163)

* Start expansion

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* _template rather than .template

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Use ioutil

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Add descriptions to mapping

* Start globbing

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Tune globbing

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Re-arrange imports

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Don't expand git hooks

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Add glob tests for .giteatemplate

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Parse globs separately so they can be tested more easily

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Change template location and add docs

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* nit

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Update docs/content/doc/features/gitea-directory.md

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>
* Update docs/content/doc/features/gitea-directory.md

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>
* Add upper-lower case match

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Nits

Signed-off-by: jolheiser <john.olheiser@gmail.com>
* Update models/repo_generate.go

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>