Fix the input parameter types accepted by the Ethernet IP PLC block for PLC reads/writes

[shntu]

What does this PR do?

This PR fixes a mismatch in the input types accepted by the tags_to_write function - tags_to_read needs a LIST_OF_VALUES_KIND since it specifies a list of keys for which values need to be read.

For tags_to_write we need to use a DICTIONARY_KIND since these are key/value pairs that need to be written.

Type of Change

• Bug fix (non-breaking change that fixes an issue)

Testing

• I have tested this change locally
• I have added/updated tests for this change

Test details:

I included a set of unit tests that check the behavior of this block against a mocked server - also tested the code against a local development server.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in hard-to-understand areas
• My changes generate no new warnings or errors
• I have updated the documentation accordingly (if applicable)

Additional Context

Currently, this block allows users to read from a PLC properly, but the tag writing functionality does not work when a workflow output step is used because of a mismatch in the expected type.

[shntu]

LIST_OF_VALUES_KIND is incorrect here - when writing, we want a dictionary to match the Dict[str, Union[int, float, str]] in the previous line

[shntu]

This block also does not include support for the regular Selector