fix: uses pascal case for `RealMouseUpOptions' and 'RealMouseDownOptions'

[nicklemmon]

Resolves #611

This is somewhat of a breaking change - maybe should not be included until the next major release.

[what-the-diff]

PR Summary

• Interface Name Standardization in mouseDown.ts
  The name of the interface realMouseDownOptions has been altered to RealMouseDownOptions, adhering to a standardized naming convention, increasing readability and consistency throughout the code.

• Interface Name Standardization in mouseUp.ts
  Similarly, in the mouseUp.ts file, realMouseUpOptions has been renamed to RealMouseUpOptions, ensuring that naming within the code maintains a consistent style, enhancing comprehensibility.