[BUG] Postgres VectorStore: TypeORMVectorStore issue with NULL characters and doesn't allow configuring content column name

[JJK801]

Describe the bug As Flowise Postgres VectorStore node uses TypeORMVectorStore, it doesn't deals with 0x00 characters from documents, leading to au postgres insert error.

It also enforce content column name to be pageContent (while PGVectorStore default is text, but allows to change it)

To Reproduce Steps to reproduce the behavior:

1. Create a chatflow with Postgres as a vector store
2. try to load this document: https://sonoff.tech/wp-content/uploads/2021/03/%E8%AF%B4%E6%98%8E%E4%B9%A6-DUALR3-V1.0-20210305.pdf
3. PG doesn't insert due to error

Expected behavior

• Use PGVectorStore instead of TypeORMVectorStore (maybe make it configurable ?)
• Add additional configurations for customizing columns names

[JJK801]

i can make a PR if needed