feat: Spring Boot config files in repos

application*.properties/.yml and bootstrap* files tracked by git are
listed under Repos, with their secret-looking keys as secrets.

- Keys whose name ends like a secret (password, secret, token, key, …)
  or whose value looks like one (Jasypt ENC(...), a URL or connection
  string with a password) are listed; providers.repos.spring.keys and
  .values replace the patterns, also in a repo's .lazysecrets.yaml.
- A file's details count the keys left out; ${VAR} values are marked
  as references, and a tracked file is only marked red when a listed
  value is in plain text.
- Later YAML/properties documents name their keys after the profile:
  spring.datasource.password (prod).
- Maven's @placeholders@ parse; Argo CD's applications.yaml and Helm
  templates aren't Spring files.
- A green leaf icon, themeable with springColor.

docs/config.md

@@ -74,6 +74,7 @@ theme:
   azureColor: ["#82aaff"]
   databricksColor: ["#ff757f"]
   repoColor: ["#c099ff"]
+  springColor: ["#c3e88d"]               # Spring Boot config files
 ```
 
 A role lazysecrets doesn't know, a typo or one from a newer version, is