gh-159643: Fix EOFError in tarfile stream mode with bz2, xz and zstd

[digit50]

closes #159643

In stream mode (r|bz2, r|xz, r|zst, and r|* when it detects one of them), _Stream._read called decompress(b"") on a decompressor that had already reached the end of its data, because an exhausted BZ2Decompressor, LZMADecompressor or ZstdDecompressor reports needs_input as false. That raised a bare EOFError whenever tarfile read past the end of the compressed stream, for example with ignore_zeros=True or on an archive without end-of-archive blocks.

This change stops the read loop once the decompressor reports eof, which matches what the code did before the gh-121109 rewrite. The gzip branch is unchanged.

The new tests in StreamReadTest (run for plain, gzip, bz2, xz and zstd streams) read two concatenated archives with ignore_zeros=True and an archive that has no end-of-archive blocks, and check that the expected member names come back. Both fail with EOFError for bz2, xz and zstd without the fix.

• Issue: tarfile stream mode raises EOFError reading past the end of bz2/xz/zstd data #159643

[python-cla-bot]

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