fix: do not auto link url from text if already inside a link

[KaneFreeman]

Resolves #854

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[codecov]

Codecov Report

Merging #857 (b433d07) into main (4325905) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #857   +/-   ##
=======================================
  Coverage   50.97%   50.97%           
=======================================
  Files         219      219           
  Lines        9538     9536    -2     
  Branches     2562     2562           
=======================================
- Hits         4862     4861    -1     
+ Misses       4295     4294    -1     
  Partials      381      381           

Files Changed	Coverage Δ
...ages/core/src/widgets/relation/RelationControl.tsx	91.37% <ø> (+0.47%)	⬆️
...markdown/plate/serialization/slate/autoLinkUrls.ts	100.00% <100.00%> (ø)