refactor(element-command): fix error message

Use 'strategy' values in error messages.
refactor(protocol): use strategy value in error message
refactor(test): fix expected test error messages 

This is b/c the 'find-element-strategy' cut-off
the first character from selector for certain
strategies.
refactor(attributeContains): use locator-strategy
test(mocks): add some more mocked responses
fix(_waitForElement): set selector to strategy value