[POC] Disallow "optional chaining" and "nullish coalescing" operators

[rgaignault]

Motivation

Changes

Test instructions

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.

[datadog-datadog-prod-us1]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

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[cit-pr-commenter]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	150.63 KiB	148.26 KiB	-2424 B	-1.57%	✅
Rum Recorder	17.91 KiB	17.88 KiB	-31 B	-0.17%	✅
Rum Profiler	5.17 KiB	5.10 KiB	-71 B	-1.34%	✅
Logs	54.02 KiB	53.18 KiB	-857 B	-1.55%	✅
Flagging	0 B	931 B	931 B	N/A%	✅
Rum Slim	109.14 KiB	106.84 KiB	-2354 B	-2.11%	✅
Worker	23.60 KiB	23.60 KiB	0 B	0.00%	✅

🚀 CPU Performance

Action Name	Base Average Cpu Time (ms)	Local Average Cpu Time (ms)	𝚫
addglobalcontext	0.010	0.011	0.001
addaction	0.024	0.036	0.013
addtiming	0.005	0.009	0.004
adderror	0.023	0.039	0.017
startstopsessionreplayrecording	0.004	0.006	0.002
startview	0.009	0.013	0.005
logmessage	0.025	0.038	0.013

🧠 Memory Performance

Action Name	Base Consumption Memory (bytes)	Local Consumption Memory (bytes)	𝚫 (bytes)
addglobalcontext	26.33 KiB	26.99 KiB	677 B
addaction	43.44 KiB	43.97 KiB	537 B
addtiming	24.71 KiB	24.95 KiB	243 B
adderror	49.54 KiB	49.54 KiB	-3 B
startstopsessionreplayrecording	23.55 KiB	23.45 KiB	-100 B
startview	420.19 KiB	425.02 KiB	4.83 KiB
logmessage	96.93 KiB	41.88 KiB	-56372 B

🔗 RealWorld