Added PHPSTAN_FAIL_WITHOUT_RESULT_CACHE env var

[staabm]

to allow testing of the result-cache lets add a new env var a new cli option, which we can use to instruct phpstan to exit with code=2, when the result cache was not used

see phpstan/phpstan#9857 (comment)

partly reverts #2608

---

➜  bug8778 git:(bug8778) ../../phpstan clear-result-cache -q; ../../phpstan analyse -q                                            
➜  bug8778 git:(bug8778) ../../../phpstan-src/bin/phpstan analyse -vvv --generate-baseline --fail-without-result-cache
Note: Using configuration file /Users/staabm/workspace/phpstan/e2e/bug8778/phpstan.neon.
Result cache not used because the metadata do not match.
 2/2 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%  1 sec/1 sec 

Result cache is saved.

                                                                                                                        
 [OK] Baseline generated with 1 error.                                                                                  
                                                                                                                        

Used memory: 78 MB
➜  bug8778 git:(bug8778) echo $?
2

[ondrejmirtes]

I agree that the error formatter was the wrong direction. But instead of env variable, I'd prefer --fail-without-result-cache CLI option :)

[staabm]

here you are

➜  bug8778 git:(bug8778) ../../phpstan clear-result-cache -q; ../../phpstan analyse -q                                            
➜  bug8778 git:(bug8778) ../../../phpstan-src/bin/phpstan analyse -vvv --generate-baseline --fail-without-result-cache
Note: Using configuration file /Users/staabm/workspace/phpstan/e2e/bug8778/phpstan.neon.
Result cache not used because the metadata do not match.
 2/2 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%  1 sec/1 sec 

Result cache is saved.

                                                                                                                        
 [OK] Baseline generated with 1 error.                                                                                  
                                                                                                                        

Used memory: 78 MB
➜  bug8778 git:(bug8778) echo $?
2

[ondrejmirtes]

Thank you.