Move blob data provider to postcard; support no_std

[Manishearth]

Progress towards #812

It can be made no_std, unlike bincode

[codecov-commenter]

Codecov Report

Merging #878 (497dc1a) into main (09d5aef) will increase coverage by 0.05%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##             main     #878      +/-   ##
==========================================
+ Coverage   74.32%   74.37%   +0.05%     
==========================================
  Files         206      206              
  Lines       13042    13058      +16     
==========================================
+ Hits         9693     9712      +19     
+ Misses       3349     3346       -3     

Impacted Files	Coverage Δ
provider/blob/src/lib.rs	100.00% <ø> (ø)
provider/blob/src/path_util.rs	100.00% <ø> (ø)
tools/datagen/src/bin/datagen.rs	0.57% <0.00%> (ø)
tools/datagen/src/main.rs	33.33% <ø> (ø)
provider/blob/src/static_data_provider.rs	54.54% <50.00%> (ø)
provider/blob/src/export/blob_exporter.rs	94.44% <100.00%> (-2.78%)	⬇️
experimental/provider_ppucd/src/parse_ppucd.rs	93.13% <0.00%> (+0.13%)	⬆️
components/datetime/src/skeleton.rs	82.48% <0.00%> (+0.45%)	⬆️
components/datetime/src/fields/symbols.rs	69.34% <0.00%> (+0.76%)	⬆️
... and 2 more

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[coveralls]

Pull Request Test Coverage Report for Build fd6d64bda5f50a51449e87ce82639f7ed7762120-PR-878

• 9 of 11 (81.82%) changed or added relevant lines in 3 files are covered.
• 17 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.05%) to 74.438%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
provider/blob/src/static_data_provider.rs	1	2	50.0%
tools/datagen/src/bin/datagen.rs	0	1	0.0%

Files with Coverage Reduction	New Missed Lines	%
provider/blob/src/export/blob_exporter.rs	1	94.44%
components/datetime/src/skeleton.rs	16	82.48%

Totals
Change from base Build 09d5aef92cd37de4e51c53e0b1eb03abb1ce8543:	0.05%
Covered Lines:	9843
Relevant Lines:	13223

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💛 - Coveralls

[sffc]

Nice! Thanks! The testdata file went from 837K to 568K too :)

[Manishearth]

Nice! Thanks! The testdata file went from 837K to 568K too :)

ooh, nice