Use valid categories in library.properties of bundled libraries (#8221)

When using previous IDE versions, the use of an invalid category value caused a warning to be displayed on every compilation:

WARNING: Category 'Network' in library lwIP_PPP is not valid. Setting to 'Uncategorized'
WARNING: Category 'Network' in library lwIP_enc28j60 is not valid. Setting to 'Uncategorized'
WARNING: Category 'Network' in library lwIP_w5500 is not valid. Setting to 'Uncategorized'
WARNING: Category 'Network' in library lwIP_w5500 is not valid. Setting to 'Uncategorized'

List of valid category values:
https://arduino.github.io/arduino-cli/latest/library-specification/#libraryproperties-file-format

Author: per1234

libraries/lwIP_PPP/library.properties

@@ -4,7 +4,7 @@ author=lwIP
 maintainer=esp8266/Arduino
 sentence=PPP interface
 paragraph=PPP interface for esp8266 arduino
-category=Network
+category=Communication
 url=https://github.com/esp8266/Arduino
 architectures=esp8266
 dot_a_linkage=true

libraries/lwIP_enc28j60/library.properties

@@ -4,7 +4,7 @@ author=Nicholas Humfrey
 maintainer=esp8266/Arduino
 sentence=Ethernet driver
 paragraph=ENC28J60 ethernet drivers for lwIP and esp8266 Arduino from https://github.com/njh/EtherSia/tree/master/src/enc28j60.cpp
-category=Network
+category=Communication
 url=https://github.com/esp8266/Arduino
 architectures=esp8266
 dot_a_linkage=true

libraries/lwIP_w5100/library.properties

@@ -4,7 +4,7 @@ author=Nicholas Humfrey
 maintainer=esp8266/Arduino
 sentence=Ethernet driver
 paragraph=Wiznet5100 ethernet drivers for lwIP and esp8266 Arduino from https://github.com/njh/W5100MacRaw
-category=Network
+category=Communication
 url=https://github.com/esp8266/Arduino
 architectures=esp8266
 dot_a_linkage=true

libraries/lwIP_w5500/library.properties

@@ -4,7 +4,7 @@ author=Nicholas Humfrey
 maintainer=esp8266/Arduino
 sentence=Ethernet driver
 paragraph=Wiznet5500 ethernet drivers for lwIP and esp8266 Arduino from https://github.com/njh/W5500MacRaw
-category=Network
+category=Communication
 url=https://github.com/esp8266/Arduino
 architectures=esp8266
 dot_a_linkage=true