Fix unstable Wi-Fi on NixOS

[kachick]

• Install iw in Linux
• Disable wifi power_save to fix unstable Wi-Fi

Attempt to fix #663

[kachick]

Before

>dmesg | grep -i power
[47143.338290] wlp3s0: Limiting TX power to 30 (30 - 0) dBm as advertised by ...

>1! iw dev wlp3s0 info
Interface wlp3s0
	ifindex 3
	wdev 0x1
	addr ...
	ssid ...
	type managed
	wiphy 0
	channel 44 (5220 MHz), width: 80 MHz, center1: 5210 MHz
	txpower 20.00 dBm
	multicast TXQ:
		qsz-byt	qsz-pkt	flows	drops	marks	overlmt	hashcol	tx-bytes	tx-packets
		0	0	0	0	0	0	0	0		0

> iw dev wlp3s0 get power_save
Power save: on

After

> iw dev wlp3s0 get power_save
Power save: off

> iw dev wlp3s0 info | grep -Pv 'ssid|addr'
Interface wlp3s0
	ifindex 3
	wdev 0x1
	type managed
	wiphy 0
	channel 44 (5220 MHz), width: 80 MHz, center1: 5210 MHz
	txpower 20.00 dBm
	multicast TXQ:
		qsz-byt	qsz-pkt	flows	drops	marks	overlmt	hashcol	tx-bytes	tx-packets
		0	0	0	0	0	0	0	0		0

[kachick]

Give it a try!