Result-Cache: Indicate key differences in cache metadata

[staabm]

the goal of this PR is to ease debugging why/which result cache metadata is different.

before this PR its pretty hard to e.g. in CI get an idea why the result cache metadata did not match and which of the key-indicators is the cause.

After this change the console output looks like:
note the new keys at the end of the error message

after changes in the composer.lock

➜  phpstan-src git:(1.10.x) ✗ php bin/phpstan -vvv
Note: Using configuration file /Users/staabm/workspace/phpstan-src/phpstan.neon.dist.
Result cache not used because the metadata do not match: projectConfig, composerLocks
 1561/1561 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100% 21 secs/21 secs

Result cache is saved.

or when no cache is present:

➜  phpstan-src git:(1.10.x) ✗ php bin/phpstan -vvv
Note: Using configuration file /Users/staabm/workspace/phpstan-src/phpstan.neon.dist.
Result cache not used because the metadata do not match: phpstanVersion, projectConfig, composerLocks, composerInstalled
 1561/1561 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100% 25 secs/25 secs

Result cache is saved.

or when the level changes

php bin/phpstan -vvv
Note: Using configuration file /Users/staabm/workspace/phpstan-src/phpstan.neon.dist.
Result cache not used because the metadata do not match: projectConfig, level
    0/1561 [░░░░░░░░░░░░░░░░░░░░░░░░░░░░]   0% < 1 sec/< 1 sec

etc.

[ondrejmirtes]

Thank you.

[janedbal]

Thank you!