* fix panic when diff

* improve code

* fix org visibility bug

* fix permission check

* add integration tests

* fix tests

* change test user name for easier maintainance and fix test

* fix test git repo name

* Support searching commits with prefix syntax

For now, support auther: committer:
When more than one prefix is supplied is presented, the result is the union.
When different prefixes are supplied, the result is the intersection.

For example,
"author:alice author:bob"
=> the result is all commits authored by Alice OR Bob

"hello committer:alice"
=> the result is all commits committed by Alice AND has the keyword
'hello' in the message.

Note that there should NOT have any space after the colon(:) of the prefix.
For example,
"author:bill" => correct
"author: bill" => wrong

* Remove unneeded logging

* Add missing files of test repository

* Add missing repo_unit entries to test fixtures

* Update test cases

* Add tooltip for commits search button

* Update tooltip text

I have no idea about how to format it with line breaks.

* Make the usage example more real

* Add a test case

* Add new options struct for SearchCommits

* Prefer len(s) > 0 over s != ""

* Add NewSearchCommitsOptions

* Fix test : make coverage -> test

* Refactor integration tests to be able to run them in parallel

* Add custom local repository temp path

* improve integration test to resue models/fixtures and store git repos with source

* use gitea-integration-meta dir instead .tar.gz and cleanup every before every test

* fix import package name