Add a HINT and a directive to match all CoreLibs apps

**Problem:** We have 4 platforms, based on CoreLibs, and directives

- `adguard_app_windows` — AdGuard for Windows
- `adguard_app_mac` — AdGuard for Mac
- `adguard_app_cli` — AdGuard for Linux
- `adguard_app_android` — AdGuard for Android

and hints

- `windows` — AdGuard for Windows
- `mac` — AdGuard for Mac
- `cli` — AdGuard for Linux
- `android` — AdGuard for Android

Now, when solving problems common to all these programs, we need to list all directives or HINTS. The directive is excessively long and difficult to read.

**Proposed solution:**

Add:
- a directive for all CoreLibs programs
`adguard_app_cl`
- a hint for all CoreLibs programs
`apps_cl` or something like that.