[OpenAPI] Use invariant culture for TextWriter

[martincostello]

Use invariant culture for TextWriter

Use culture-invariant TextWriter implementation for OpenAPI.

Description

• Ensure OpenAPI documents are written to a culture-invariant TextWriter implementation.
• Add/update unit/integration tests to ensure the invariant culture is used to generate the OpenAPI document regardless of the current culture.
• Add support for emitting exclusiveMinimum/exclusiveMaximum instead of minimum/maximum where relevant based on the values of RangeAttribute properties.

~~I couldn't replicate this issue in .NET 10, I'm guessing Microsoft.OpenApi has had some internal refactoring that means that it's no longer using an overload on TextWriter that was hitting this (unless I messed up my test to repro it somehow).~~

• Contributes to #60628.
• Contributes to #61965.