fread NUL follow up

[mattdowle]

Follow up to #3433 for #3400
Closes #3400
Closes #2435

• Added news item and Roy to contributor list.
• the file added for test 2025 has an extra line of data after the NUL. It stops on the NUL silently currently. I'd lean towards skipping the NUL with warning and then proceeding as if the NUL wasn't there, which in this case would reading the extra line of data. Note the difference between cat and more :

$ more issue_3400_fread.txt 
a=b
A  B  C
1  2  3
3  2  1
$ cat issue_3400_fread.txt 
a=b
A  B  C
1  2  3
3  2  1
4  5  6

• address all issues with NUL inside fields as well as after newline, close all issues linked from [bug] fread handling embedded NUL characters #3400 and add more tests

[codecov]

Codecov Report

Merging #3505 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3505   +/-   ##
=======================================
  Coverage   96.66%   96.66%           
=======================================
  Files          65       65           
  Lines       12277    12277           
=======================================
  Hits        11867    11867           
  Misses        410      410

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[codecov]

Codecov Report

Merging #3505 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3505      +/-   ##
==========================================
- Coverage   96.66%   96.66%   -0.01%     
==========================================
  Files          65       65              
  Lines       12280    12278       -2     
==========================================
- Hits        11870    11868       -2     
  Misses        410      410

Impacted Files	Coverage Δ
src/fread.c	98.49% <100%> (-0.01%)	⬇️

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