new(engine): enforce unique exceptions names

[mrgian]

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind feature

/kind release

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area build

/area engine

/area tests

/area proposals

/area CI

What this PR does / why we need it:
Does't allow multiple exceptions definitions in the same rule object.
Example:

- rule: test_rule
  desc: test rule
  condition: proc.cmdline contains curl
  output: command=%proc.cmdline
  priority: INFO
  exceptions:
    - name: test_exception
      fields: [proc.cmdline]
      comps: [contains]
      values:
        - [curl 127.0.0.1]
    - name: test_exception
      fields: [proc.cmdline]
      comps: [endswith]
      values:
        - [curl 127.0.0.1]

- rule: test_rule
  exceptions:
    - name: test_exception
      values:
        - [curl 1.1.1.1]
  append: true

In this example it's not clear where the new values are appended.
Which issue(s) this PR fixes: #2279

Fixes #2279

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

new(engine): enforce unique exceptions names

[github-actions]

This PR may bring feature or behavior changes in the Falco engine and may require the engine version to be bumped.

Please double check userspace/engine/falco_engine_version.h file. See versioning for FALCO_ENGINE_VERSION.

/hold

[poiana]

LGTM label has been added.

Git tree hash: 244d440edb2e293be72260047f16d6273885de0a

[leogr]

This PR may bring feature or behavior changes in the Falco engine and may require the engine version to be bumped.

Please double check userspace/engine/falco_engine_version.h file. See versioning for FALCO_ENGINE_VERSION.

/hold

Already bumped.
/unhold

[FedeDP]

@mrgian can you rebase to fix conflicts?

[FedeDP]

/approve

[poiana]

LGTM label has been added.

Git tree hash: a16401be9b2826992037d6a0adb403aecb895751

[mrgian]

@mrgian can you rebase to fix conflicts?

Rebased!

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: FedeDP, leogr, mrgian

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