lyrics: probe text codec before reading

Reason for the change

For non-English (or say, non-Latin language) user, it's somewhat common to see user have non-ASCII lyrics file. This patch make use of KCodecs to probe the text codec and use the probe result to decode the text document.

Test plan

Use Kate to convert some sidecar lyrics file (suggest to contain non-ascii characters, like lyrics for CJK song) to non-ASCII format (e.g. UTF-8, GB18030, Shift-JIS), and then try to use Elisa play song with such lyrics file.

Screenshots or screen recordings

Before	After

Bugs fixed