feat!: add `Definition::Sequence::length_range` field

[mina86]

Having a length_range field in the Sequence definition allows to better specify encoding formats for bounded vectors. This in turn helps with performing calculations such as figuring out the maximum or minimum length of encoding of a type.

[dj8yfo]

@mina86 you want this or

    Sequence {    // replaces `Array` and supports varint
        length_width: u8,
        min_length: u64,
        max_length: u64,
        elements: Declaration,
    },

[mina86]

I’m gonig to add length_width and replace Array in next PR.