pcbnew: Via net change should not force net change of touching copper

Description

Try to change VIA name while via is on pad, you will be forced to change net for pad also.

• Part of #5484 (closed)

Steps to reproduce

1. Place VIA on pad (noname_2.kicad_pcb);
2. Change VIA net (via VIA properties dialog);
3. User is forced to change PAD net also or discard net changes of parent dialog

• does step 3 canceling also discards other via changed properties? - it is unclear.

I think, confirmation dialog should be changed as following.

Make three buttons instead of two:

1. "Cancel": will return to parent "VIA properties" dialog, nothing changed (this is a new action);
2. "Apply NET for VIA": change net for VIA only and close both dialogs (this is a new action, expected default behavior);
3. "Change NET for all copper": change net name for all copper (current "Change nets" button behavior) and close both dialogs.

OR, my preferred way:

• get rid of confirmation dialog at all, accepting action no 2 from previous change list as default. This will improve workflow (no disruptions).

cnjUdarDOG

KiCad Version

Application: Pcbnew

Version: (5.99.0-8143-gf7b20611c1), release build

Libraries:
	wxWidgets 3.0.5
	libcurl/7.71.0 OpenSSL/1.1.1g (Schannel) zlib/1.2.11 brotli/1.0.7 libidn2/2.3.0 libpsl/0.21.0 (+libidn2/2.3.0) libssh2/1.9.0 nghttp2/1.41.0

Platform: Windows 10 (build 19042), 64-bit edition, 64 bit, Little endian, wxMSW

Build Info:
	Date: Jan  5 2021 13:50:08
	wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8)
	Boost: 1.73.0
	OCE: 6.9.1
	Curl: 7.71.0
	ngspice: 32
	Compiler: GCC 10.2.0 with C++ ABI 1014

Build settings:
	KICAD_SCRIPTING=ON
	KICAD_SCRIPTING_MODULES=ON
	KICAD_SCRIPTING_PYTHON3=OFF
	KICAD_SCRIPTING_WXPYTHON=ON
	KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
	KICAD_SCRIPTING_ACTION_MENU=ON
	KICAD_USE_OCE=ON
	KICAD_SPICE=ON