[feature] add falco as source for datadog events

[maxd-wttj]

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

Any specific area of the project related to this PR?

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

/area build

/area config

/area outputs

/area tests

What this PR does / why we need it:

This PR adds a "falco" source tag to events sent to Datadog. Currently, these events are only tagged according to the Falco event source, and the Datadog default "my apps" tag, which makes targeting all falco events in datadog quite cumbersome. With an additional "falco" tag, it is now easier to filter falco events.

Before:

After:

Which issue(s) this PR fixes:

Fixes #1017

Special notes for your reviewer:

[poiana]

Welcome @maxd-wttj! It looks like this is your first PR to falcosecurity/falcosidekick 🎉

[poiana]

LGTM label has been added.

Git tree hash: cea7c51f675cbc2a680bc08e0ff7519af6f5aaf8

[Issif]

An unit test is failing:

 === RUN   TestNewDatadogPayload
    datadog_test.go:24: 
            Error Trace:    /home/runner/work/falcosidekick/falcosidekick/outputs/datadog_test.go:24
            Error:          Not equal: 
                            expected: outputs.datadogPayload{Title:"Test rule", Text:"This is a test from falcosidekick", AlertType:"info", SourceType:"falco", Tags:[]string{"proc.name:falcosidekick", "source:syscalls", "hostname:test-host", "example", "test"}}
                            actual  : outputs.datadogPayload{Title:"Test rule", Text:"This is a test from falcosidekick", AlertType:"info", SourceType:"falco", Tags:[]string{"proc.name:falcosidekick", "source:syscalls", "source:falco", "hostname:test-host", "example", "test"}}

                            Diff:
                            --- Expected
                            +++ Actual
                            @@ -5,5 +5,6 @@
                              SourceType: (string) (len=5) "falco",
                            - Tags: ([]string) (len=5) {
                            + Tags: ([]string) (len=6) {
                               (string) (len=23) "proc.name:falcosidekick",
                               (string) (len=15) "source:syscalls",
                            +  (string) (len=12) "source:falco",
                               (string) (len=18) "hostname:test-host",
            Test:           TestNewDatadogPayload

[maxd-wttj]

An unit test is failing:

 === RUN   TestNewDatadogPayload
    datadog_test.go:24: 
          Error Trace:    /home/runner/work/falcosidekick/falcosidekick/outputs/datadog_test.go:24
          Error:          Not equal: 
                          expected: outputs.datadogPayload{Title:"Test rule", Text:"This is a test from falcosidekick", AlertType:"info", SourceType:"falco", Tags:[]string{"proc.name:falcosidekick", "source:syscalls", "hostname:test-host", "example", "test"}}
                          actual  : outputs.datadogPayload{Title:"Test rule", Text:"This is a test from falcosidekick", AlertType:"info", SourceType:"falco", Tags:[]string{"proc.name:falcosidekick", "source:syscalls", "source:falco", "hostname:test-host", "example", "test"}}

                          Diff:
                          --- Expected
                          +++ Actual
                          @@ -5,5 +5,6 @@
                            SourceType: (string) (len=5) "falco",
                          - Tags: ([]string) (len=5) {
                          + Tags: ([]string) (len=6) {
                             (string) (len=23) "proc.name:falcosidekick",
                             (string) (len=15) "source:syscalls",
                          +  (string) (len=12) "source:falco",
                             (string) (len=18) "hostname:test-host",
          Test:           TestNewDatadogPayload

I'll check the test and update accordingly

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Issif, maxd-wttj

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/falcosecurity/falcosidekick/blob/master/OWNERS)~~ [Issif] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[poiana]

LGTM label has been added.

Git tree hash: a447964562e4d89721765f01b84d77c5e1b1ea4e