Extend underscore naming strategy for camelCase properties with uppercase sequences

[sherifss]

The current underscore naming strategy incorrectly converts camelCase property names that contain two consecutive uppercase letters. Examples below:

Before:

$myXVariable → my_xvariable
$allowedXAmount → allowed_xamount

After:

$myXVariable → my_x_variable
$allowedXAmount → allowed_x_amount

Previously, this required explicitly specifying the column name in the mapping. This change adjusts the regex to handle uppercase sequences while preserving existing behavior for other cases.

[greg0ire]

I'm afraid this is a breaking change.

Looking at the history, we take changes to column name seriously: #7908

[sherifss]

@greg0ire Thank you very much for the context.
Do you think it is appropriate for this use case if I add a new opt-in naming strategy?