[wip] Prevent useless strings creations during applyCollectionDiff

[freedge]

before:

following this change my terraform plan goes from 120s to 100s.

this is more a fyi as this pr is made against v1.17.2 (as used on my provider) but the main branch seems to use the same logic.

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[bflad]

Hi @freedge 👋 Thank you for submitting this. Please note that terraform-plugin-sdk v1 has been end-of-life since July 31, 2021, therefore we are not accepting any changes to that code since it will never be released. Peeking at the changes, they appear fairly trivial in nature so we would consider something like this for v2, if you're interested. There is a terraform-plugin-sdk v2 upgrade guide available, although depending on the provider size, it may be worth skipping over to terraform-plugin-framework instead at this point.

[github-actions]

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