Issue #11 & #153 fix - IsAnagram

[alev-98]

Description

Closes: #11 & #153
This PR fixes the IsAnagram method, making it so strings with the same characters, but different amount of them, will no longer be treated as anagrams.

The solution creates a list from the source string while the other string is enumerated to remove each char from the list. If a char could not be removed from the list, false is immediately returned.

The first commit adds a failing test: "aab" and "abb" (#153) which should result in false but doesn't.
The second commit fixes the method and the resulting test is now false and passes.

Checklist

• An issue was first created before opening this pull request
• The new code follows the contribution guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
  i believe comments are not necessary in this case
• I have made corresponding changes to the documentation
  i didn't since the nature of this pr
• My changes generate no new warnings
• I have added tests to ensure that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes