Use uv for package installation if available

[grischard]

The framework currently installs a few packages by calling pip directly:

https://github.com/platformio/platform-espressif32/blob/master/builder/frameworks/espidf.py

The new-ish uv is much faster than pip. This matters especially when compiling on low power devices like a Raspberry Pi.

If uv is installed, pip should be called as uv pip instead.

[Jason2866]

Pip installs needed packages one time only. Same as for tools and toolchains. There is no speed increase when compile is done the 2nd time.

[grischard]

Yes, but in a build system like esphome, it happens every time a compile environment gets created, for every single device. This environment gets re-created every new version. The savings over time would therefore be significant.

(Yes, some caching there would improve thing seriously; both of these things are true)