Bp2build support for sdk_version and java_version.

This CL adds java_version and sdk_version support to bp2build
converters for
   - java library
   - java binary
   - android library
   - android binary
   - android library import

Although java import doesn't support java_version and sdk_version, the
neverlink java_library wrapper around a java_import must specify a
sdk_version when targetting a device. "none" is used by convention.

Change-Id: I22a69dea2e351858368df69ed6a703b568d613ea
Bug: 215230098
Test: Presubmits
diff --git a/bp2build/android_app_conversion_test.go b/bp2build/android_app_conversion_test.go
index ef3f124..928a1f2 100644
--- a/bp2build/android_app_conversion_test.go
+++ b/bp2build/android_app_conversion_test.go
@@ -53,6 +53,7 @@
 				"srcs":           `["app.java"]`,
 				"manifest":       `"AndroidManifest.xml"`,
 				"resource_files": `["res/res.png"]`,
+				"sdk_version":    `"current"`,
 			}),
 		}})
 }
@@ -91,7 +92,8 @@
     ]`,
 				"custom_package":   `"com.google"`,
 				"deps":             `[":static_lib_dep"]`,
-				"javacopts":        `["-source 1.7 -target 1.7"]`,
+				"java_version":     `"7"`,
+				"sdk_version":      `"current"`,
 				"certificate_name": `"foocert"`,
 			}),
 		}})
@@ -131,6 +133,7 @@
     })`,
 				"manifest":       `"AndroidManifest.xml"`,
 				"resource_files": `["res/res.png"]`,
+				"sdk_version":    `"current"`,
 			}),
 		}})
 }
@@ -365,6 +368,7 @@
 				"manifest_values": `{
         "minSdkVersion": "24",
     }`,
+				"sdk_version": `"current"`,
 			}),
 		}})
 }
@@ -388,6 +392,7 @@
 				"manifest_values": `{
         "minSdkVersion": "30",
     }`,
+				"sdk_version": `"30"`,
 			}),
 		}})
 }