Handle leading zeros in scientific notation literals

[WardBrian]

I'm performing some fuzzing for #1100 and it found this bug which exists independently of that PR. The AST to MIR translation currently avoids trimming a leading zero if the next character is e or ., but not E, leading to (in this case) failures in the partial evaluator at --O1.

Submission Checklist

• [x] Run unit tests
• Documentation
  • [ ] If a user-facing facing change was made, the documentation PR is here:
  • [x] OR, no user-facing changes were made

Release notes

Fixed an issue with leading zeroes in real literals like 0E0

Copyright and Licensing

By submitting this pull request, the copyright holder is agreeing to license the submitted work under the BSD 3-clause license (https://opensource.org/licenses/BSD-3-Clause)

[codecov[bot]]

Codecov Report

Merging #1336 (20c3078) into master (464e4dc) will not change coverage. The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master    #1336   +/-   ##
=======================================
  Coverage   88.77%   88.77%           
=======================================
  Files          64       64           
  Lines        9873     9873           
=======================================
  Hits         8765     8765           
  Misses       1108     1108           

Impacted Files	Coverage Δ
src/frontend/Ast_to_Mir.ml	92.25% <0.00%> (ø)