feature: Allow different row heights in block diagram

[DoubleLT]

Description

In below is an example of the test, just to show the problem:

block-beta
    columns 1

    block: b_demo_libs
        demoone
    end

    block: b_demo_minus_one_libs
        columns 5
        demolibs_01
        demolibs_02
        demolibs_03
        demolibs_04
        space
        demolibs_05
        demolibs_06
        space:3
        demolibs_07
        demolibs_08
        space:3
        demolibs_09
        demolibs_10
    end

    block: b_minus_two_libs
        demo_m2_01
        demo_m2_02      
        demo_m2_03
    end

And the image shows:

Steps to reproduce

1. Mermaid Live Editor
2. input the above code
3. you'll find the height is the same for each subblock group, which is more convenient for automatic height not the same height.

Screenshots

No response

Code Sample

Setup

• Mermaid version:
• Browser and Version: [Chrome, Edge, Firefox]

Suggested Solutions

No response

Additional Context

No response

[shubhamparikh2704]

Hi @DoubleLT , thanks for reporting. We really appreciate it. If you have any proposal for syntax please onto the comment.