Improvement: Display TV Show specials in logical order inside seasons

[wutschel]

Description

Closes #57.

Usually, TV Show specials are listed under season 0. Many TV Shows have special episodes which are important to watch in logical order, ex. "Doctor Who". Kodi is able to display special episodes in both season 0 and in the correct place inside the common seasons. This PR implements the same functionality based on information shared within #57 and links provided from there.

To allow correct logical sorting, the Kodi API shares specialsortseason and specialsortepisode, which represent the logical position of the special episode inside the common seasons. The app does now request this information to
show special episodes in both season 0 and the logical position. 3-staged sorting is applied to ensure the special episodes are added in correct order to the desired position.

To differentiate special episodes from common episodes the naming convention for track numbers and episode IDs is adapted. It follows Kodi's implementation by using "Sx" (x = special episode) which clearly visualizes the type of episode.

Screenshots, suing dummy database with episodes from "Doctor Who":

Summary for release notes

Improvement: Display TV Show specials in logical order inside seasons

[wutschel]

btw, I am quite sure this also fixes potential sorting problems with episodes. I have seen while testing this PR, that sometimes the order of episodes was wrong.

[kodiai]

Partial review -- timed out after analyzing 0 of 3 files (346s).

Retry skipped -- this repo has timed out frequently for this author.
Consider splitting large PRs to stay within the review timeout budget.

Review timed out before producing output. Retry skipped due to frequent timeouts for this repo/author.