Add gitlab repository information retrieval support:

* Create RepositoryStatsUpdater type to use as interface over updaters
* Add RepositoryStatsUpdater instance to global contexts so they can be used in CrateDetails
* Add Pool field into RepositoryStatsUpdater
* Return a default icon
* Add mock tests for github and gitlab updaters

Author: GuillaumeGomez

Cargo.lock

@@ -102,6 +102,7 @@ procfs = "0.7"
 criterion = "0.3"
 kuchiki = "0.8"
 rand = "0.8"
+mockito = "0.29"
 
 [build-dependencies]
 time = "0.1"

Cargo.toml

@@ -190,8 +190,10 @@ docker-compose run -- database add-directory <DIRECTORY> [PREFIX]
 # Updates github stats for crates.
 # You need to set CRATESFYI_GITHUB_USERNAME, CRATESFYI_GITHUB_ACCESSTOKEN
 # environment variables in order to run this command.
+# Set DOCSRS_GITLAB_ACCESSTOKEN to raise the rate limit,
+# or leave it blank to fetch repositories at a slower rate.
 # You can set this environment variables in ~/.cratesfyi.env file.
-docker-compose run -- database update-github-fields
+cargo run -- database update-repository-fields
 ```
 
 If you want to explore or edit database manually, you can connect to the database