updates ios_command to use network_cli plugin (#19992)

* refactors ios_command to use network_cli
* adds unit test cases for ios_command

test/units/modules/network/ios/fixtures/show_version

@@ -0,0 +1,45 @@
+Cisco IOS Software, IOSv Software (VIOS-ADVENTERPRISEK9-M), Version 15.6(1)T, RELEASE SOFTWARE (fc1)
+Technical Support: http://www.cisco.com/techsupport
+Copyright (c) 1986-2015 by Cisco Systems, Inc.
+Compiled Fri 20-Nov-15 13:39 by prod_rel_team
+
+
+ROM: Bootstrap program is IOSv
+
+ios01 uptime is 7 weeks, 5 days, 11 hours, 14 minutes
+System returned to ROM by reload
+System image file is "flash0:/vios-adventerprisek9-m"
+Last reload reason: Unknown reason
+
+
+
+This product contains cryptographic features and is subject to United
+States and local country laws governing import, export, transfer and
+use. Delivery of Cisco cryptographic products does not imply
+third-party authority to import, export, distribute or use encryption.
+Importers, exporters, distributors and users are responsible for
+compliance with U.S. and local country laws. By using this product you
+agree to comply with applicable laws and regulations. If you are unable
+to comply with U.S. and local laws, return this product immediately.
+
+A summary of U.S. laws governing Cisco cryptographic products may be found at:
+http://www.cisco.com/wwl/export/crypto/tool/stqrg.html
+
+If you require further assistance please contact us by sending email to
+export@cisco.com.
+
+Cisco IOSv (revision 1.0) with  with 472441K/50176K bytes of memory.
+Processor board ID 99I10YFMUCJ3JEZMV4DQB
+3 Gigabit Ethernet interfaces
+DRAM configuration is 72 bits wide with parity disabled.
+256K bytes of non-volatile configuration memory.
+2097152K bytes of ATA System CompactFlash 0 (Read/Write)
+0K bytes of ATA CompactFlash 1 (Read/Write)
+0K bytes of ATA CompactFlash 2 (Read/Write)
+10080K bytes of ATA CompactFlash 3 (Read/Write)
+
+
+
+Configuration register is 0x0
+
+