(Supernova): Fix all typescript migration leftovers for Silences

[barsukov]

Fix all typescript migration leftovers for Silences

Sub-tasks
Please have a look on all silences/* folder and fix related files, this is aprx, files and count of errors:

• 8 src/components/silences/CreateSilence.tsx:39
• 6 src/components/silences/ExpireSilence.tsx:13
• 4 src/components/silences/RecreateSilence.tsx:121
• 1 src/components/silences/silenceHelpers.ts:46
• 25 src/components/silences/SilenceScheduled.tsx:7
• 6 src/components/silences/SilencesList.tsx:41
• 4 src/components/StoreProvider.tsx:7
• 1 src/helpers.ts:9

Additional Context
Sometimes you will need to fix few other staff, try to minimaze it, keep PRs small and easy to review.