The config file format changed. The tool golangci-lint migrate
was used to migrate the old config. However old comments and also
the structure of the disabled linters was preserved.
Moreover the new v2 version introduced new linters, we disable
3 of them because they are very noise and we do not really want
to check for them: funcorder, noinlineerr, embeddedstructfieldcheck.
Add this file both to the main LND directory so that devs can use it for
local linter runs and also add it to the `tools` directory so that the
docker environment used to run the linter in CI has access to it. A
custom linter binary can be built via `golangci-lint custom`. This will
pull in and register all the plugins listed in the new config file when
building the new binary. The new binary can then be run using
`custom-gcl run`.