"Find All Elements" issue with backslashes in Name or AutomationId

[tpfahler]

Example:
The address bar in a simple "open file" dialogue on a Windows 11 system has AutomationId 1001:

However if the selected directory is C:\Windows, the element Name is "Addresse: C:\Windows" and
FlaUILibrary.Find All Elements //*[@AutomationId="1001"]
will fail with
[ FAIL ] error: bad escape \W at position 19
because of the "\W" part in the Name property.
We had similar issues with AutomationIds which contain backslashes, e.g. "Table\1;1".

I think the root cause is in robotframework-flaui/src/.../util/automationelement.py, in the method _get_argument_in_xpath:
The implementation uses regex to build the xpath string properties for AutomationId, Name and ClassName, but the substitution is very likely to fail if the replacement value contains a backslash. The python doc states: "if it is a string, any backslash escapes in it are processed."
When we feed the name "Addresse: C:\Windows" to the python code,
re.sub(r"\[\d+]", "[@Name=\"Adresse: C:\\Windows\"]", "Foo[1]")
will throw exactly the same error message as the FlaUILibrary keyword in the example above.

I suggest the following fix, inspired by the comment at the end of the section in the python doc:

Replace line 34 in automationelement.py
xpaths[-1] = re.sub(r"\[\d+]", argument, xpaths[-1])
with
xpaths[-1] = re.sub(r"\[\d+]", argument.replace('\\',r'\\'), xpaths[-1])