[libc] Tracking Issue - Emulated Float128 and Float80 in LLVM Libc

### This issue tracks work related to introducing emulated `Float128` and `Float80` support.
Discourse: https://discourse.llvm.org/t/gsoc-2026-libc-enable-float80-and-float128-math-support-on-unsupported-targets-for-llvm-libc/

## Float128

#### Introduce `Float128` and its operators overloads

- https://github.com/llvm/llvm-project/pull/200565

## Float80

#### Introduce `Float80`

- https://github.com/llvm/llvm-project/pull/214447

#### Add operator overloads for `Float80`

- https://github.com/llvm/llvm-project/pull/214493

## Misc

- https://github.com/llvm/llvm-project/pull/206277

- https://github.com/llvm/llvm-project/pull/200907

- https://github.com/llvm/llvm-project/pull/211593

- https://github.com/llvm/llvm-project/pull/213422

- https://github.com/llvm/llvm-project/pull/217344

- https://github.com/llvm/llvm-project/pull/215657

- https://github.com/llvm/llvm-project/pull/215605

## Verify/ Test/Modify math functions for emulated `Float128`

- https://github.com/llvm/llvm-project/issues/216576