Add some more files to .gitignore

- `compile_commands.json`: clang compilation database
- `.ccls-cache`: Cache directory for the ccls language server
- `.clang-format`: clang formatting description
5 jobs for master in 3 minutes and 20 seconds (queued for 20 seconds)
Status Name Job ID Coverage
  Build
passed build:lib #23256
docker

00:01:39

 
  Test
passed test:lib #23257
docker

00:01:40

 
  Trigger
passed trigger:android

passed trigger:javascript

passed trigger:python