[bug] Fix SettingWithCopyWarning and export error

[boyestrous]

Description

• Summary of the change / bug fix.

1. Fixes SettingWithCopyWarning from Pandas in the stocks/options and stocks/ba modules\
2. Also fixes error with stocks/ba --export flag (it was unable to export)
3. Created unit tests for google_view.py and helper_funcs.py that would have caught the export flag issue
4. Updated Docstrings for the impacted functions

• Link [Bug]stocks/ba/queries - google_view.py: SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame. #1862

• Screenshot of the feature or the bug before/after the fix, if applicable. N/A

• Relevant motivation and context.

  Nobody likes seeing warnings, we need to be assured that we're not inadvertently dropping relevant data from the DF in these functions.

• List any dependencies that are required for this change.
  none

How has this been tested?

• Please describe the tests that you ran to verify your changes.
  Compared raw output from the google_model to the actual output. I left a detailed explanation of the cause of the SettingWithCopyWarning in the issue.

  TL;DR version - the warning only intermittently appears because of the varying data returned from google. Creating a copy of the original DF after filtering removes this warning.

• Provide instructions so we can reproduce.

for changes in yfinance_model.py - unit tests already exist and continued to work

I tested the removal of the warning by running the following command before and after adding my changes
/stocks/options/chains

for changes to stocks/ba

I wrote a pytest called test_display_queries in test_google_view to compare the expected stdout. (I followed the Contributing guidelines for pytests visualizations)

I manually verified the output of the functions (prior to writing the pytest) with the following steps:

1. open a python terminal

2. import the following

   from openbb_terminal.common.behavioural_analysis import google_model as gm
   from openbb_terminal.common.behavioural_analysis import google_view as gv
   import pandas as pd
   

3. get the response from google_model, save as gm_response
   >>> gm_response = gm.get_queries('TSLA')

4. print the 'top' df from within gm_response
   >>> gm_response['TSLA']['top']

5. run the following and verify that the top X values match the dict from the previous one
   gv.display_queries('TSLA')

• Please also list any relevant details for your test configuration.

Checklist:

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Others

• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• My code passes all the checks pylint, flake8, black, ... To speed up development you should run pre-commit install.
• New and existing unit tests pass locally with my changes. You can test this locally using pytest tests/....