Add git.Blob Fuzz Target

[DaveLak]

Adds a new fuzz target for git.Blob, using fuzzed data for all __init__ arguments.

60 second local test run output:

INFO: A corpus is not provided, starting from an empty corpus
#2	INITED cov: 211 ft: 211 corp: 1/1b exec/s: 0 rss: 72Mb
#10	NEW    cov: 230 ft: 232 corp: 2/4b lim: 4 exec/s: 0 rss: 74Mb L: 3/3 MS: 2 InsertByte-InsertByte-
#26	NEW    cov: 230 ft: 251 corp: 3/7b lim: 4 exec/s: 0 rss: 76Mb L: 3/3 MS: 1 ChangeByte-
#128	pulse  cov: 230 ft: 251 corp: 3/7b lim: 4 exec/s: 64 rss: 77Mb
#181	REDUCE cov: 230 ft: 251 corp: 3/6b lim: 4 exec/s: 60 rss: 77Mb L: 2/3 MS: 4 ChangeBinInt-CopyPart-EraseBytes-ChangeBit-
#256	pulse  cov: 230 ft: 251 corp: 3/6b lim: 4 exec/s: 64 rss: 77Mb
#512	pulse  cov: 230 ft: 251 corp: 3/6b lim: 6 exec/s: 56 rss: 77Mb
#1024	pulse  cov: 230 ft: 251 corp: 3/6b lim: 11 exec/s: 56 rss: 77Mb
#1919	NEW    cov: 239 ft: 260 corp: 4/27b lim: 21 exec/s: 56 rss: 77Mb L: 21/21 MS: 1 InsertRepeatedBytes-
#1926	REDUCE cov: 239 ft: 260 corp: 4/26b lim: 21 exec/s: 56 rss: 77Mb L: 20/20 MS: 2 ChangeBit-EraseBytes-
#2048	pulse  cov: 239 ft: 260 corp: 4/26b lim: 21 exec/s: 55 rss: 77Mb
#2122	REDUCE cov: 239 ft: 260 corp: 4/25b lim: 21 exec/s: 55 rss: 77Mb L: 1/20 MS: 1 EraseBytes-
#2537	REDUCE cov: 281 ft: 302 corp: 5/50b lim: 25 exec/s: 56 rss: 78Mb L: 25/25 MS: 4 ChangeBit-InsertRepeatedBytes-ChangeBinInt-ChangeBinInt-
#3382	DONE   cov: 281 ft: 302 corp: 5/50b lim: 33 exec/s: 55 rss: 78Mb
Done 3382 runs in 61 second(s)
stat::number_of_executed_units: 3382
stat::average_exec_per_sec:     55
stat::new_units_added:          7
stat::slowest_unit_time_sec:    0
stat::peak_rss_mb:              78

[Byron]

Thanks a lot!

It's a bit unpleasant to see that that the git.Blob has a path associated to it, as if it was always read from a loose object, with IO then dominating the runtime. I'd always hope there are ways to trigger the important code without touching disk for it.