Move CID-related constants to FVM-owned crates.

[lemmih]

Summary of changes
Changes introduced in this pull request:

• Use shared code from FVM crates.
• We still need the 'forest_cid' crates due to json support.

Reference issue to close (if applicable)

Other information and links

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (main@d846152). Click here to learn what that means.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1543   +/-   ##
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  Coverage        ?   25.61%           
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  Files           ?      289           
  Lines           ?    24261           
  Branches        ?        0           
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  Hits            ?     6215           
  Misses          ?    18046           
  Partials        ?        0           

Impacted Files	Coverage Δ
ipld/cid/src/lib.rs	100.00% <ø> (ø)
ipld/cid/tests/base_cid_tests.rs	100.00% <100.00%> (ø)

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[connormullett]

LGTM!