Avoid decoding long runs in a single thread

[gerashegalov]

Description

Split long runs among threads

Lead Co-authored-by: @abellina
Co-authored-by: @gerashegalov

Benchmarks

Generated files with a single integer column comprised of logically ~1 billion rows valued 1.

• 4 pages. with 250 million rows per page
• 32 pages, with 33 million rows per page
• 1024 pages, 1 million row per page
• 4475 pages, 240 thousand rows

The benchmark Spark app iterates these files and executes

spark.read.parquet(path).selectExpr("SUM(ones)") 

gpuDecodePageDataGeneric nsys the PR branch vs branch-24.10

branch	time	registers per thread	shared mem executed	theoretical occupancy	latency
24.10	1.762 s	72	32,768	87.5 %	9.632 μs
PR	1.911 s	64	65,536	100 %	10.028 μs

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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[gerashegalov]

Investigating a bug in this PR where batch_len goes negative on a 33M-row run:

DEBUG thread=96 warp_id=3 warp_lane=0 => batch_len=-8 negative=1 (size=33554423 remaining=96 max_count=526848, last_run_pos=526856)

[gerashegalov]

Negative batch fixed with 09dd99e