feat: define policy.monitor policy scope

[ndr-brt]

What this PR changes/adds

Define a new policy.monitor scope that will be used by the policy monitor, on which the ContractExpiryCheckFunction is defined by default

Why it does that

policy monitor

Further notes

List other areas of code that have changed but are not necessarily linked to the main feature. This could be method
signature changes, package declarations, bugs that were encountered and were fixed inline, etc.

Linked Issue(s)

Closes #3482

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[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (9d39f5c) 72.07% compared to head (3622e61) 72.18%.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3518      +/-   ##
==========================================
+ Coverage   72.07%   72.18%   +0.11%     
==========================================
  Files         848      848              
  Lines       17092    17095       +3     
  Branches      958      958              
==========================================
+ Hits        12319    12340      +21     
+ Misses       4366     4348      -18     
  Partials      407      407              

Files	Coverage Δ
...ector/core/policy/ContractExpiryCheckFunction.java	77.27% <ø> (ø)
.../edc/connector/contract/ContractCoreExtension.java	84.84% <ø> (ø)
...nnector/policy/monitor/PolicyMonitorExtension.java	80.76% <100.00%> (+80.76%)	⬆️
...licy/monitor/manager/PolicyMonitorManagerImpl.java	100.00% <100.00%> (ø)

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