BREAKING(csv): remove `csv` from module names

[iuioiua]

What's changed

The csv-* prefix has been removed from module names in @std/csv. In other words:

1. @std/csv/csv-parse-stream has moved to @std/csv/parse-stream.
2. @std/csv/csv-stringify-stream has moved to @std/csv/stringify-stream.

Motivations

These changes were made to shorten these module specifiers while still retaining their context; that they're CSV-oriented streams.

Migration guide

To migrate:

1. Import from @std/csv/parse-stream instead of @std/csv/csv-parse-stream.

   - import { CsvParseStream } from "@std/csv/csv-parse-stream";
   + import { CsvParseStream } from "@std/csv/parse-stream";
   
   // ...

2. Import from @std/csv/stringify-stream instead of @std/csv/csv-stringify-stream.

   - import { CsvStringifyStream } from "@std/csv/csv-stringify-stream";
   + import { CsvStringifyStream } from "@std/csv/stringify-stream";
   
   // ...

---

Towards #5177.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 93.34%. Comparing base (4052256) to head (c81d4e0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #5172 +/- ## ======================================= Coverage 93.34% 93.34% ======================================= Files 469 469 Lines 37917 37917 Branches 5386 5386 ======================================= Hits 35392 35392 Misses 2483 2483 Partials 42 42 ```

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