Migrate test function creation/editing/view to flow diagram service#700

LakshanWeerasinghe wants to merge 4 commits intoballerina-platform:1.6.xballerina-platform/ballerina-language-server:1.6.xfrom

LakshanWeerasinghe:fix#2405LakshanWeerasinghe/ballerina-language-server:fix#2405Copy head branch name to clipboard