fix: use SI decimal file size units

[naveensingh]

Type of change(s)

• Bug fix
• Feature / enhancement
• Infrastructure / tooling (CI, build, deps, tests)
• Documentation

What changed and why

Updated formatSize() helpers to divide by 1000 instead of 1024.

Tests performed

• Confirmed file size in all apps that rely on formatSize()

Closes the following issue(s)

• Closes Allow to display file/storage sizes in decimal base General-Discussion#794

Checklist

• I read the contribution guidelines.
• I manually tested my changes on device/emulator (if applicable).
• I updated the "Unreleased" section in CHANGELOG.md (if applicable).
• I have self-reviewed my pull request (no typos, formatting errors, etc.).
• All checks are passing.

[roxwize]

I can't say I'm fond of this change. A way to revert back to standard 1,024 divisors for file size would be nice. My file manager does it this way and having there now be an obvious discrepancy in the representation of filesizes between the two is troublesome.

I never really understood using SI prefixes anyways? Computers work in powers of two, there isn't really a benefit I can think of to representing them in a way that, in binary, uses a totally arbitrary number.