patch 9.1.1007: filetype: various ignore are not recognized

patch 9.1.1007: filetype: various ignore are not recognized

Problem:  filetype: various ignore are not recognized
Solution: detect rg/docker/npm/vvsce ignore files as 'gitgnore' filetype
          (Wu, Zhenyu)

Not only prettier, but many programs also support ignore files (like rg,
docker, npm, vscode). So use the gitignore filetype for them due to same syntax

closes: #16428

Signed-off-by: Wu, Zhenyu <wuzhenyu@ustc.edu>
Signed-off-by: Christian Brabandt <cb@256bit.org>