VyOS v1.4 support for BGP (T6892 & T6888 & T6822) (#367)

• VyOS v1.4 support for BGP (T6892)

• WIP: chnages to scanners and facts for BGP on v1.4

• scanners and facts modification to support as_numberless commands

• remove optional regex groups

• VyOS v1.4 BGP system-as functionality

• bgp_af linter

• bgp_global mods and testing

• bgp_global v.1.4 support

• linter fixes

• bgp_global and bgp_af fixed 1.3 test cases

• unit tests for bgp modules for both versions

• obsolete stranzas removed from bgp_global for both versions

• some typos removed

• bgp_global rst updates

• t6829 related draft changes

• Draft changes to unit tests fot original set and t6888 updates

• changelog

• D.R.Y for bgp_global and testmodule names

• linter fixes

• fixtures for bgp_af options testts

• stranzas options processing

• T6888 bgp option test func and cases

• clean-up draft code and update to rm_templates

• v14 system-as change supported in conf and tests

• T6822 BGP global passive bugfix

• clean-up

• T6829: update integration tests

• T6829: fix integration tests for global

• T6829: fix integration tests for bgp_global

• T6829: fix for 1.4 AF integration tests

• T6829: fix unit tests after removing obsolete items

• T6829: fix sanity test failures

• T6829: fix documentation

• Lint and comments are addressed

• rtt.yaml and fix to integration tests

• updated fragments for bgp_global

• lint fixes

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Co-authored-by: Gaige B. Paulsen <gaige@cluetrust.com>