top: Replace upip with mip everywhere.

Updates all README.md and docs, and manifests to `require("mip")`.

Also extend and improve the documentation on freezing and packaging.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

ports/esp32/boards/manifest.py

@@ -1,11 +1,10 @@
 freeze("$(PORT_DIR)/modules")
-module("upip.py", base_path="$(MPY_DIR)/tools", opt=3)
-module("upip_utarfile.py", base_path="$(MPY_DIR)/tools", opt=3)
 include("$(MPY_DIR)/extmod/uasyncio")
 
 # Require some micropython-lib modules.
 require("dht")
 require("ds18x20")
+require("mip")
 require("neopixel")
 require("ntptime")
 require("onewire")