feat(core & modbus tcp): test read tag

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 53.16092% with 163 lines in your changes missing coverage. Please review.

Project coverage is 75.81%. Comparing base (4b0532f) to head (5925bf2).

Files	Patch %	Lines
plugins/modbus/modbus_req.c	37.85%	110 Missing :warning:
plugins/modbus/modbus_stack.c	38.70%	38 Missing :warning:
src/parser/neu_json_rw.c	78.94%	12 Missing :warning:
src/adapter/driver/driver.c	88.88%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2076 +/- ## ========================================== - Coverage 76.22% 75.81% -0.42% ========================================== Files 104 104 Lines 18447 18789 +342 ========================================== + Hits 14061 14244 +183 - Misses 4386 4545 +159 ```

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