When adding a command, use some heuristics to ensure the command is executed in the root of a project

[markpollack]

Adding a command will add files into the directory ./spring/commands and also add a README-.md file. If a user does the following

spring boot new
spring command add --from https://github.com/rd-1-2022/udc-asa 

the the command is not added to the directory where the new project was created.

On heuristic is to check for a pom.xml or build.gradle file, and if not found, issue a warning that indicates it was not added to a project directory, and print out the name of the directory where the commands were added - this can help to indicate a mistake was made. Maybe command add should fail instead of display a warning?