fix: evaluate zoom-dependent symbol sizes at the drawn zoom (#8175)

* fix: evaluate zoom-dependent symbol sizes at the drawn zoom

* Refactor: extract symbol size helpers, move comments to tsdoc

* Test: cover the retained-tile label size in a render test

* Merge branch 'main' into camera-size-drawn-zoom

* Revert: cover the retained-tile label size in a render test

* Test: Improve symbol_size test coverage

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Co-authored-by: Harel M <harel.mazor@gmail.com>