GitHub actions should support multiple include paths #74
Description
Problem to Solve
The grpc-generator command supports specifying --proto-include-path multiple times, but the GitHub Actions workflows' proto-include-path input supports only a single string.
Proposed Solution
workflow_call inputs support only the types boolean, number, and string, so the easiest solution is to treat the proto-include-path input as a space-delimited list and add the prefix --proto-include-path to each element.