Add a syscall to sign with endorsement key

[srasoamiaramanana-ledger]

Description

This PR adds the syscall os_endorsement_key1_sign_without_code_hash that signs data with the endorsement key without adding the application's code hash to the data to sign.

Changes include

• Bugfix (non-breaking change that solves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)
• Tests
• Documentation
• Other (for changes that might not fit in any category)

Breaking changes

New syscall.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (033ef9f) 59.47% compared to head (6357c14) 59.47%.
Report is 10 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #466   +/-   ##
=======================================
  Coverage   59.47%   59.47%           
=======================================
  Files          12       12           
  Lines        1683     1683           
=======================================
  Hits         1001     1001           
  Misses        682      682           

Flag	Coverage Δ
unittests	59.47% <ø> (ø)

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