Instead of being a `Record<string, ShapeHandler>`, the type now knows
every key in the variable.

All of the shapes in
`packages/mermaid/src/rendering-util/rendering-elements/shapes/` use
`D3.Selection`s as input parameters and as return parameters.

Although, for some reason, passing them to roughjs seems to work?

Convert the
`packages/mermaid/src/rendering-util/rendering-elements/nodes.js`
file to TypeScript at
`packages/mermaid/src/rendering-util/rendering-elements/nodes.ts`

Convert the
`packages/mermaid/src/rendering-util/rendering-elements/shapes/util.js`
file to TypeScript at:
`packages/mermaid/src/rendering-util/rendering-elements/shapes/util.ts`.

This let's us confirm that the types we're passing to `insertNode()` are
valid.

See: mermaid-js#5974 (comment)
See: mermaid-js#5974 (comment)

Co-authored-by: saurabhg772244 <[email protected]>

I don't know what exactly the type does or is for, but I've tried to
type it to what it seems to be.

Handle `NaN` values by using `parseFontSize()`.

Suggested-by: mermaid-js#5974 (comment)

Suggested-by: mermaid-js#5974 (comment)
Co-authored-by: Sidharth Vinod <[email protected]>