[WIP]Support for Multi modbus hub

[crhan]

Description:

There is a feature request at https://community.home-assistant.io/t/ability-to-add-multiple-modbus-hubs/16365

This PR is try to implement this feature.

Now modbus components can have a config key named "hub_name". If not provided, the default value "default" is used. So this PR does not break the current config.

Related issue (if applicable):

Pull request in home-assistant.io with documentation (if applicable): home-assistant/home-assistant.io#<home-assistant.io PR number goes here>

Example entry for configuration.yaml (if applicable):

modbus:
  - type: rtuovertcp
    host: 192.168.15.129
    port: 8887
    hub_name: ventilation
sensor:
- platform: modbus
  scan_interval: 5
  registers:
  - name: ventilation_operation_mode
    slave: 1
    register: 2
    register_type: holding
    count: 1
    hub_name: ventilation 
  - name: ventilation_fan_mode
    slave: 1
    register: 3
    register_type: holding
    count: 1
    hub_name: ventilation

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.

If the code does not interact with devices:

• Tests have been added to verify that the new code works.

[houndci-bot]

Some files could not be reviewed due to errors:

Traceback (most recent call last):

Traceback (most recent call last):
  File "/home/linters/.local/bin/flake8", line 7, in 
    from flake8.main.cli import main
ModuleNotFoundError: No module named 'flake8'

[houndci-bot]

Some files could not be reviewed due to errors:

Traceback (most recent call last):

Traceback (most recent call last):
  File "/home/linters/.local/bin/flake8", line 7, in 
    from flake8.main.cli import main
ModuleNotFoundError: No module named 'flake8'

[frenck]

Could not find a related PR in our documentation repository. Adding docs-missing label.

[balloob]

There are a lot of unrelated changes in this PR making it very hard to see what has actually changed. I'm assuming you're using some auto formatter. Please update your PR to not contain any unrelated style changes.

[benvm]

I am very much interested in this, so I thought I'd help out a bit with these changes.

Also, Travis CI detected a problem in components/climate/flexit.py
I updated that to the new implementation. Unfortunately I can't really test that component.

@crhan I can't directly contribute to your PR but commits are in my own fork:
style changes in: 813d077
flexit update in: 3149ec6

[crhan]

Thank you all and @benvm your commit is cherry-picked to my branch.

Sorry I don't have enough time to complete this PR very soon. But this feature is worked in my house since I submit this PR. So basically this feature works well.

[benvm]

Thank you for this work.
I have created a new PR #19726, so it is easier for me to make further changes.

[balloob]

Closing this in favor of #19726