[pyOpenSci review] remove imports from function scope wherever possible

[rich-iannone]

From the pyOpenSci comment:

issue (_boxhead.py, _formats.py, _modify_rows.py, _spanners.py, _utils_nanoplots.py, others): I can spot a few places where we could move some import statements to the top of the file instead of being in functions. AFAICT there is no circular import issue there, and it does not seem to be for performance reasons either.

pyOpenSci/software-submission#202 (comment)

[rich-iannone]

List of functions that contain imports:

• cols_label(): from great_tables._helpers import UnitStr
• save(): import base64
• save(): from ._utils_selenium import _get_web_driver
• _save_screenshot(): from io import BytesIO
• _save_screenshot(): from selenium.webdriver.common.by import By
• _save_screenshot(): from selenium.webdriver.support import expected_conditions as EC
• _save_screenshot(): from selenium.webdriver.support.ui import WebDriverWait
• _save_screenshot(): from PIL import Image
• fmt_units(): from great_tables._helpers import define_units
• FmtImage/to_latex(): from warnings import warn
• FmtImage/to_latex(): from ._gt_data import FormatterSkipElement
• FmtIcon/to_latex(): from warnings import warn
• FmtIcon/to_latex(): from ._gt_data import FormatterSkipElement
• FmtFlag/to_latex(): from warnings import warn
• FmtFlag/to_latex(): from ._gt_data import FormatterSkipElement
• fmt_nanoplot(): from great_tables._utils import _str_detect
• fmt_nanoplot(): from great_tables._utils import _flatten_list
• GroupRows: from ._tbl_data import group_splits
• _remove_from_body_styles(): from ._utils_render_html import _is_loc
• _remove_from_body_styles(): from ._locations import LocBody
• opt_table_font(): from great_tables._helpers import system_fonts
• infer_render_env(): import IPython
• tab_spanner(): from great_tables._helpers import UnitStr
• Html/to_latex(): from ._utils_render_latex import _not_implemented
• _format_number_compactly(): from great_tables.vals import fmt_currency, fmt_scientific, fmt_integer, fmt_number
• _is_intlike(): import numbers
• _is_intlike(): from decimal import Decimal
• _remove_exponent(): from decimal import Decimal, InvalidOperation
• _render_as_html(): from ._scss import compile_scss

[machow]

We plan to circle back to this, and have noted it, but I'm going to close here for now.