Lock during uv sync, uv add and uv remove to avoid race conditions

[konstin]

Surprisingly, we weren't locking during uv sync so far, so running uv sync in parallel could cause errors in filesystem races.

I've also added locks to uv add and uv remove which concurrently modify pyproject.toml. These locks only apply after we determined the interpreter, so they don't actually prevent computing the same thing twice when running uv add in parallel.

All other subcommands that I checked were already locking (with no claim to exhaustiveness)

Fixes #12751

Test Plan

I don't have CI-sized reproducer for this.

[project]
name = "debug"
version = "0.1.0"
requires-python = ">=3.12"
dependencies = [
  "boto3>=1.38.30",
  "fastapi>=0.115.12",
  "numba>=0.61.2",
  "polars>=1.30.0",
  "protobuf>=6.31.1",
  "pyarrow>=20.0.0",
  "pydantic>=2.11.5",
  "requests>=2.32.3",
  "urllib3>=2.4.0",
  "scikit-learn>=1.6.1",
  "jupyter>=1.1.1",
]

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"

rm -rf .venv && parallel -n0 "uv sync -q" ::: {1..10}

[leviska]

Does this also lock on uv run if it needs sync?

[Gankra]

uv version also presumably needs this

[konstin]

Tracking follow-ups in #13883