Adding features to simpPRU

Building upon the work done in GSoC 2021 to make programming the PRU easier for beginners, this project aims to add tests, features, and more compatibility for simpPRU, the simple Python-like language that compiles to PRU C and runs natively on the PRU. I will be adding assignment,bitwise operators which increase the efficiency of usage and write testcases for it, adding the compiler flags for generated C code and document their outcomes,the python test would be added to github actions for testsuite,I will be adding support for return statements,calling C from simpPRU,enhance error handling in parser,adding additional testcases for the features present. I will be writing a research paper on simpPRU quoting its need,implementation done and its preferable usage.This will make the overall language more robust and efficient, which will help beginners who are learning to use the PRU or experienced users prototyping something on the PRU.