Added new keychain path log

[omarzl]

This pull request adds a log after the keychain is created:

INFO: Running command line: bazel-bin/Sources/SignHereTool/sign-here create-keychain --keychain-name TestKeychain --keychain-password ***
Keychain created in the path: /Users/omarzl/Library/Keychains/TestKeychain-db

This small change can add these improvements:

• There is a log that confirms to the user that the keychain was created
• It is a sanity check that guarantees that they keychain was created by calling security list-keychains

Added tests for the new error types:

bazel test //Tests/...
//Tests/SignHereLibraryTests:SignHereUnitTests                  (cached) PASSED in 0.6s
    PASSED  .Tests/SignHereLibraryTests/SignHereUnitTests.test-runner.sh (0.0s)
Test cases: finished with 1 passing and 0 failing out of 1 test cases

[omarzl]

I got these changes, not sure if I should discard them

[tinder-maxwellelliott]

Looks okay

[tinder-maxwellelliott]

Thank you for adding this!