fix: repartitioned reads of CSV with custom line terminator

[korowa]

Which issue does this PR close?

Closes #12328.

Rationale for this change

At this moment DF is unable to properly identify ranges after file repartitioning for CSV files with custom line terminator (bound calculation function considers only \n as a line separating character).

Test failures are caused by target_partitions = 4 (default for Datafusion sqllogictests engine/runner) and set repartition_file_min_size = 1 in csv_files.slt executed before failing test -- these two settings trigger scan repartitioning, which is not supported.

What changes are included in this PR?

File scan repartitioning functions used for plain-text files (CSV and NDJson -- though json reader don't have line separator option in its API) now aware of line terminator character.

Are these changes tested?

Sqllogictests for single-thread reading and repartitioned reading of CSV with custom line separator.

Are there any user-facing changes?

No.

[alamb]

Thank you @korowa -- this makes sense to me

I also ran the tests in this PR without the corresponding code change and verified the test failed (and thus covers the feature)

Running "csv_files.slt"
External error: query failed: DataFusion error: Object Store error: Generic LocalFileSystem error: Requested range was invalid
[SQL] select * from stored_table_with_cr_terminator order by col1;
at test_files/csv_files.slt:369

Error: Execution("1 failures")
error: test failed, to rerun pass `-p datafusion-sqllogictest --test sqllogictests`

Caused by:
  process didn't exit successfully: `/Users/andrewlamb/Software/datafusion/target/debug/deps/sqllogictests-7c41483884b46406 csv_file` (exit status: 1)