* don't advertise IPv6 in VNet when IPv6 is disabled on host
* show ipv6 disabled in VNet diag report
* add platformHostIPv6Disabled stub for unsupported OSes
* fix some nits
* add dns diagnostic check proto
* add DNSServerSuffix and DNSServerPort constants
* handle dns diagnostic probe queries
* add dns diagnostic check
* enable dns diagnostic check in Connect
* run dns diagnostic check in tsh vnet
* render dns diagnostic check in Connect
* fix some nits
* move ssh diag check after dns check
* handle dns diagnostic probe A queries
* add dns diagnostic check proto for A queries
* refactor dns diagnostic check to also check A records
* refactor Connect to also render dns diagnostic A records
* drop trailing dot from dns diag probe
* add tests for dns diag text rendering
* do not fail dns diag if any nameserver is reachable
* Adjust spacing between DNS diag success/warning rows
* fix some nits
* improve rendering of dns reachability errors
---------
Co-authored-by: Maja Cieślak <maja.cieslak@goteleport.com>
* lib/vnet: add `EmbeddedVNet` type
* lib/vnet/dns: make it possible to use `/etc/resolv.conf` on Linux
* Use FakeHostNetwork in vnet_test.go
* Close host-side TUN
* Link to the `/etc/resolv.conf` man page
* Extend the host network ready timeout for CI
* Stop using global logger unnecessarily
* Fix spelling mistakes in doc comments
* feat: added vnet support for database
* feat: handling some edge cases with db key
* minor improvements and tests
* feat: improve database certificate reissuance and enhance error handling in notifications
* splitting out teleport connect changes to separate pr
* refactor for DRY
* feat: added enforcement to get db-user from wire protocol for supported group of dbs
* added tests
* feat: added vnet filter logic to filter on vnet dns hash from status
* chore: removed db username as not supporting it now
* chore: added protocol validation
* chore: updating on pr comments
* chore: streamline fqdn resoluiont for db and better logging on db name conflict
* chore: simplify db resolution logic by handling multiple matches
Pavel