Modernise PngPredictor and refactor LzwFilter and FlateFilter to reduce memory allocation

[BobLd]

PngPredictor updated to reflect latest changes in https://github.com/apache/pdfbox/blob/trunk/pdfbox/src/main/java/org/apache/pdfbox/filter/Predictor.java#L30 and PRs that dates after first port to C#

Benchmark

Method	Job	NuGetReferences	Mean	Error	StdDev	Gen0	Gen1	Gen2	Allocated
MOZILLA_10225_0	Job-QIOSCZ	PdfPig 0.1.11-alpha-20250528-5b566	8,018.510 ms	49.5397 ms	46.3395 ms	54000.0000	43000.0000	38000.0000	2234.31 MB
MOZILLA_10225_0	Job-SLPJHD	PdfPig 0.1.11 (new)	7,993.233 ms	55.2988 ms	51.7266 ms	51000.0000	38000.0000	33000.0000	2090.44 MB
fseprd1102849	Job-QIOSCZ	PdfPig 0.1.11-alpha-20250528-5b566	396.066 ms	9.6408 ms	28.4262 ms	11500.0000	8500.0000	4000.0000	203.9 MB
fseprd1102849	Job-SLPJHD	PdfPig 0.1.11 (new)	394.410 ms	7.8609 ms	19.2828 ms	9500.0000	6500.0000	3000.0000	184.2 MB
cat_genetics_bobld	Job-QIOSCZ	PdfPig 0.1.11-alpha-20250528-5b566	7.337 ms	0.1465 ms	0.4035 ms	328.1250	164.0625	164.0625	6.05 MB
cat_genetics_bobld	Job-SLPJHD	PdfPig 0.1.11 (new)	7.061 ms	0.1639 ms	0.4622 ms	414.0625	320.3125	125.0000	5.93 MB