feat(heuristics): add whitespace, fake email, and similar project checks with tests

Implemented three new heuristics: Whitespace Check for suspicious spacing, Fake Emails for invalid maintainer addresses, and Similar Projects for duplicate structures. Added unit tests for all.

Signed-off-by: Amine <[email protected]>

Author: AmineRaouane

tests/slsa_analyzer/checks/test_detect_malicious_metadata_check.py

@@ -29,7 +29,7 @@
         # heuristic, a false negative has been introduced. Note that if the unit test were allowed to access the OSV
         # knowledge base, it would report the package as malware. However, we intentionally block unit tests
         # from reaching the network.
-        ("pkg:pypi/zlibxjson", CheckResultType.PASSED),
+        ("pkg:pypi/zlibxjson", CheckResultType.UNKNOWN),
         ("pkg:pypi/test", CheckResultType.UNKNOWN),
         ("pkg:maven:test/test", CheckResultType.UNKNOWN),
     ],