fix: 🐛 add missing customization

[apurva010]

• change the default avatar 'if the url was not provided'
• error builder for asset and network profile image
• config of emoji picker sheet
• background color of emoji picker modal sheet
• on tap of reacted user list in reaction list modal
• top padding of text field

Description

Checklist

• [x] The title of my PR starts with a Conventional Commit prefix (fix:, feat:, docs: etc).
• [x] I have followed the Contributor Guide when preparing my PR.
• [ ] I have updated/added tests for ALL new/updated/fixed functionality.
• [x] I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• [x] I have updated/added relevant examples in examples or docs.

Breaking Change?

• [ ] Yes, this PR is a breaking change.
• [x] No, this PR is not a breaking change.

Related Issues

Closes #133