Small bugfixes and improvements (#514)

# Pull Request Description

## Summary

This Pull Request includes several code improvements, refactoring,
feature additions, and documentation updates mainly focused on enhancing
the functionality and maintainability of the codebase.

## Details

### Refactoring and Improvements:

- **Commit (5ea20aa) by @ogabrielluiz**: Unnecessary indentation in the
`getPythonCode` function within `constants.tsx` has been removed to
improve code readability.

- **Commit (6886828) by @ogabrielluiz**: 
- Changed the `load_flow_from_json` function signature in `process.py`
to accept either a JSON file path or a JSON object.
- Updated the import statement for `Chain` in `base.py` to be more
explicit by importing it from `langchain.chains.base` instead of
`langflow.graph.vertex.types`.
- Removed a print statement from the `process_tweaks` function in
`process.py`.
- Added an optional `tweaks` parameter to the `load_flow_from_json`
function.
- Changed the return type of the `build` method in the `Graph` class
from `List[Vertex]` to `Chain`.

- **Commit (83c28dc) by @ogabrielluiz**: The `process_tweaks` function
in `process.py` has been refactored to improve readability and
maintainability. An `apply_tweaks` function was added to apply tweaks to
the node, and a `validate_input` function was added for input
validation. The function now raises a `ValueError` if the input is not
in the expected format.

- **Commit (11185af) by @ogabrielluiz**: Refactored the
`fix_memory_inputs` function in `process.py` to improve readability by
reducing nesting. The function now checks if the `langchain_object` has
a `memory` attribute and if it is not `None` before proceeding. The
try-except block was also refactored to reduce nesting.

- **Commit (f180fa6) by @ogabrielluiz**: The input parameter in
`process.py` has been changed to accept a `Path` object in addition to a
string or dictionary, improving the flexibility of the function and
allowing for easier file handling.

### Features:

- **Commit (8a5525f) by @ogabrielluiz**: The `getPythonCode` function in
`constants.tsx` now accepts a `tweaks` parameter which is used to
customize the behavior of the flow. A `buildTweaks` function generates
the `tweaks` object which is passed to the `load_flow_from_json`
function.

- **Commit (c5d6f48) by @ogabrielluiz**: Added a `build_and_install`
target to the `Makefile` to build the package and install it without
running it. This is useful for building and installing on a remote
server. Additionally, fixed the path to the `langflow.main` module in
the backend target of the `Makefile`.

### Documentation:

- **Commit (76a1265) by @ogabrielluiz**: Updated the Langflow API usage
example in `README.md` to reflect the new API endpoint URL. Added a new
optional `tweaks` parameter to the `run_flow` function for flow
customization and updated the example code accordingly.

### Other:

- **Commit (0dcd93e) by @lucaseduoli**: Added Discord and Twitter icons,
and GitHub stars.

- **Commit (0dcd93e) by @lucaseduoli**: Fixed the Twitter link.