## Description
This PR introduces the ability to add oneself as a signer by simply
clicking a button, rather than filling the details manually.
### "Add Myself" in the document creation flow
https://github.com/documenso/documenso/assets/25515812/0de762e3-563a-491f-a742-9078bf1d627d
### "Add Myself" in the document template creation flow
https://github.com/documenso/documenso/assets/25515812/775bae01-3f5a-4b24-abbf-a47b14ec594a
## Related Issue
Addresses
[#113](https://github.com/documenso/backlog-internal/issues/113)
## Changes Made
Added a new button that grabs the details of the logged-in user and
fills the fields *(email, name, and role)* automatically when clicked.
## Testing Performed
Tested the changes locally through the UI.
## Checklist
- [x] I have tested these changes locally and they work as expected.
- [ ] I have added/updated tests that prove the effectiveness of these
changes.
- [ ] I have updated the documentation to reflect these changes, if
applicable.
- [x] I have followed the project's coding style guidelines.
- [ ] I have addressed the code review feedback from the previous
submission, if applicable.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
- **New Features**
- Introduced the ability for users to add themselves as signers within
documents seamlessly.
- **Enhancements**
- Improved form handling logic to accommodate new self-signer
functionality.
- Enhanced user interface elements to support the addition of self as a
signer, including a new "Add myself" button and disabling input fields
during the process.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
