docs: fix 18 typos in comments and documentation

[Avicennasis]

Summary

Fix 18 typos in comments, Javadoc and one error message across 7 sample activities. All are in app/src/main/java/com/deezer/sdk/sample/.

unnecesary -> unnecessary (comment // disable unnecesary buttons)

• app/src/main/java/com/deezer/sdk/sample/EqualizerActivity.java (L77)
• app/src/main/java/com/deezer/sdk/sample/RadiosActivity.java (L107)
• app/src/main/java/com/deezer/sdk/sample/UserArtistsActivity.java (L79)
• app/src/main/java/com/deezer/sdk/sample/UserRadiosActivity.java (L109)
• app/src/main/java/com/deezer/sdk/sample/UserTopTracksActivity.java (L74)
• app/src/main/java/com/deezer/sdk/sample/VisualizerActivity.java (L84)

splitted by genre -> split by genre (Javadoc)

• app/src/main/java/com/deezer/sdk/sample/UserAlbumsActivity.java (L134)
• app/src/main/java/com/deezer/sdk/sample/RadiosActivity.java (L138)
• app/src/main/java/com/deezer/sdk/sample/UserArtistsActivity.java (L151)
• app/src/main/java/com/deezer/sdk/sample/UserTopTracksActivity.java (L139)
• app/src/main/java/com/deezer/sdk/sample/UserRadiosActivity.java (L158)

Unparsed reponse -> Unparsed response (message passed to new DeezerError(...))

• app/src/main/java/com/deezer/sdk/sample/UserAlbumsActivity.java (L163)
• app/src/main/java/com/deezer/sdk/sample/UserArtistsActivity.java (L181)
• app/src/main/java/com/deezer/sdk/sample/UserTopTracksActivity.java (L169)
• app/src/main/java/com/deezer/sdk/sample/UserRadiosActivity.java (L188)

stray of in Javadoc — The list of <x> of displayed by this activity. -> The list of <x> displayed by this activity.

• app/src/main/java/com/deezer/sdk/sample/UserAlbumsActivity.java (L43)
• app/src/main/java/com/deezer/sdk/sample/UserArtistsActivity.java (L44)
• app/src/main/java/com/deezer/sdk/sample/UserTopTracksActivity.java (L40)

(UserRadiosActivity L43 and RadiosActivity L38 already read correctly, which is what confirms the stray word.)

Notes for reviewers

• One change is inside a string literal, not a comment: the Unparsed reponse -> Unparsed response fix changes the message text of a DeezerError. It is a sample-app error message, there are no test sources in this repository and nothing asserts on the string, but please review that hunk specifically.
• No identifiers were renamed, and no logic was changed.
• The five files with CRLF line endings (RadiosActivity, UserAlbumsActivity, UserArtistsActivity, UserRadiosActivity, UserTopTracksActivity) keep their CRLF endings; EqualizerActivity and VisualizerActivity keep LF. The diff is 18 changed lines and nothing else.
• The same unnecesary / Unparsed reponse / splitted strings also occur in UserFlowActivity.java, UserCustomTrackListActivity.java, UserPlaylistsActivity.java and HomeActivity.java. Those were outside the scope of this pass and are left untouched — happy to extend the PR to cover them if you would prefer a single sweep.
• Heads-up on licensing: this repository does not carry a LICENSE file (and GitHub reports no detected license), so there is no explicit grant covering outside contributions. We noticed and wanted to flag it rather than assume. Adding one would make it clearer for future contributors.

No functional changes - comments, Javadoc and one error-message string only.