Move anti-forgery implementation in demos to shared #29709

Job	Run time
Check if tests should run	2s
Get changed demos	1s
Determine scope for framework tests	1s
${{ matrix.CONSTEL }}-${{ matrix.STRATEGY }}-${{ matrix.THEME }}	1s
Build DevExtreme	1s
Lint code base	1s
Check generated demos (changed only)	1s
Check TS	1s
Check generated demos (${{ matrix.CONSTEL }})	1s
Build Demos Bundles	1s
${{ matrix.CONSTEL }}-screenshots-${{ matrix.THEME }}	1s
${{ matrix.CONSTEL }}-screenshots-${{ matrix.THEME }}	1s
merge-artifacts	1s
	14s

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