Verify no keywords collide with Robot Framework standard library

[bollwyvl]

Description

Some custom keywords presently have the same names as keywords from Robot Framework standard library keywords (specifically XML).

Reproduce

• Use all the keywords
• see some warnings

Expected behavior

• no warnings about shadowed keywords

Context

• add a lint step that checks libdoc output against all standard library

[bollwyvl]

Breaking backwards compatibility would not be fun for this, but might be worth investigating in the future.