fixes spelling errors in comments across the codebase

[donatik27]

Changes

core/src/ecmult.rs

• // This unsafe block allocates a new, unitialized ECMultGenContext and

• // This unsafe block allocates a new, uninitialized ECMultGenContext and

core/src/field.rs

• /// The least signifiant byte is in the front.

• /// The least significant byte is in the front.

Why these changes are needed

These changes fix misspellings in the comments to improve code readability and documentation quality:

1. "unitialized" -> "uninitialized": Corrects the spelling of a common programming term
2. "signifiant" -> "significant": Fixes a typo in describing byte order

While these typos don't affect the functionality of the code, having correct spelling in documentation helps maintain professionalism and reduces potential confusion for developers reading the code.

The changes are purely cosmetic and only affect comments, with no impact on the actual code functionality.```