Support monomer to molecule connections type

[rrodionov91]

Background
Currently connections between monomers and molecules are not supported.

Solution
It needs to support it for ket and mol v3000 formats.

Proposed changes for ket:

// Connection
{
    "connectionType": "single",
    "endpoint1": {
        "monomerId": "monomer14",
        "attachmentPointId": "R3"
    },
    "endpoint2": {
        "moleculeId": "mol1",
        "atomId": "2"
    }
},

[AlexeyGirin]

Verified.

• Indigo Toolkit Version 1.21.0-rc.1.0-g9194599b2-wasm32-wasm-clang-19.0.0
• Ketcher Version 2.22.0-rc.2 Build at 2024-06-03; 18:43:00
• Chrome Version 125.0.6422.142 (Official Build) (64-bit)
• Windows 10