[Tolk] Tidy up the tests, separate into folders

This commit reorganizes tests for the compiler.
Before, they all were places in a single folder.
Now, they negative tests are separated.
Negative tests are named just `err-XXXX`, for quick
file search in IDE.

Tolk-tester can now execute tests by "contains" pattern:
> tolk-tester tests catch
will find "tests/**/*catch*.tolk"

Author: tolk-vm

tolk-tester/tests/a6.tolk renamed to tolk-tester/tests/a-tests.tolk

@@ -76,7 +76,7 @@ fun main(): int {
 }
 
 /**
-    method_id | in | out
+    method_id  | in | out
 @testcase | 0  |    | 31415926535897932384626433832795028841971693993751058209749445923078164
 
 @code_hash 84337043972311674339187056298873613816389434478842780265748859098303774481976