Rename project to Flipper Blue++

Point every app's fap_weburl at the renamed repo
(github.com/andydixon/flipper-bluepp) and recenter the build.sh header on the
full-stack BLE firmware and the app suite rather than a single app. GitHub
repo renamed from flipper-bt-inspector; the slug drops "++" since GitHub repo
names cannot contain "+".

build.sh

@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
-# Build a Flipper Zero firmware update package that contains BT Inspector.
+# Flipper Blue++ - build a Flipper Zero firmware update package with ST's full
+# BLE stack, the BLE command API exported to apps, and the Blue++ app suite.
 #
 # Why a firmware build and not a plain .fap:
 #   * The stock radio coprocessor image is ST's "BLE Light" stack: peripheral/