Do Not Track feature sends both DNT and GPC even on browsers which does not support them #1982

Issue Details

According to bugzilla/1967420, Firefox is planning to unship the DNT implementation.
See also MDN:

The whole DNT (Do Not Track) specification has been discontinued. The mechanism design was flawed, because it was a cooperative feature between users, websites, and browsers. The idea is that the user tells the website to not track them, and the website would comply. However, there is no strict enforcement of this policy, so advertisement websites ignored the DNT header and tracked users anyway. The feature is therefore useless. Moreover, it is harmful as it leaves more user fingerprint in the header, which can be used to track users even more.

Currently, both Do Not Track and Global Privacy Control headers are sent when the Ask websites not to track you option is enabled in the Tracking Protection section.
And adguard app is unable to specify that only DNT or GPC header should be sent.

Proposed solution

Do not force both the DNT and GPC headers to be sent when Ask websites not to track you enabled, and make the DNT and GPC optional.

Example:
Into the Ask websites not to track you section, there are three selectable options: 1.DNT, 2.GPC, and 3.Both.

Alternative solution

No response