chore: rename prepare.js into install-from-github.js

This is what it actually does.

Author: aslushnikov

prepare.js install-from-github.js

@@ -22,7 +22,7 @@
     "debug-test": "node --inspect-brk test/test.js",
     "test-doclint": "node utils/doclint/check_public_api/test/test.js && node utils/doclint/preprocessor/test.js",
     "test": "npm run lint --silent && npm run ccoverage && npm run fcoverage && npm run wcoverage && npm run test-doclint && node utils/testrunner/test/test.js",
-    "prepare": "node prepare.js",
+    "prepare": "node install-from-github.js",
     "lint": "([ \"$CI\" = true ] && eslint --quiet -f codeframe --ext js,ts ./src || eslint --ext js,ts ./src) && npm run tsc && npm run doc",
     "doc": "node utils/doclint/cli.js",
     "ccoverage": "cross-env COVERAGE=true npm run ctest",