Static analysis improvements

[gmponos]

Hi.. although you are not using static analysis these docblocks can improve static analysis on userland.

• I used psalm-* in order for the normal annotations to not mess the IDEs
• The psalm-* annotation works both for psalm and phpstan. I think that also psalm reads phpstan-* annotations.
• Since you don't use static analysis I only changed the public api.

More things could be done. Like adding to levels something like this:

psalm-param 100|200|300|400|550|600|LogLevel::* $level

But it wont be 100% accurate since level can accept info and INFO and iNFO so I believe it's not worth the overhead.