feat(gradle): add gradle module (#4423)

* docs: document gradle module

* implement gradle module

* gradle-module: add test for wrapper properties case

* docs: improve gradle module documentation

* fix: fix gradle module wrapper properties test

* drop gradle executable strategy

* apply suggested stuff

* Fix config schema

docs/.vuepress/public/presets/toml/plain-text-symbols.toml

@@ -64,6 +64,9 @@ symbol = "git "
 [golang]
 symbol = "go "
 
+[gradle]
+symbol = "gradle "
+
 [guix_shell]
 symbol = "guix "