Support write mode for Parquet and Avro using table property

[arina-ielchiieva]

Currently in Parquet and Avro writers write mode is hard-coded. For Parquet - overwrite, Avro - create.
This PR allows to set write mode using table properties for each of the above mentioned writers thus write mode can be controlled based on the needs of Iceberg table user.

[fbocse]

👍 nice, having the "overwrite" default makes this change backwards compatible, right?

[arina-ielchiieva]

For Parquet - yes, initially it was overwrite. For Avro - no, initially it was create. I made both overwrite to be the same but I can default Avro to create for backward compatibility if needed.

[rdblue]

Can you update the description with what this changes and why it is useful?

[arina-ielchiieva]

@rdblue updated the description.

[rdblue]

@arina-ielchiieva, why is this needed? Shouldn't the mode always be overwrite?

[arina-ielchiieva]

@rdblue
whether to overwrite file or fail when file already exists depends on application strategy:

1. if you are confident that you always create unique files and then somehow collision has occurred, you would prefer to know that something went wrong rather than implicitly overwriting the file.
2. on the other hand, when creating a several files: some files were created successfully, some were not, and you have retry strategy that attempts to create the same files one more time, in this case overwrite mode maybe more preferable.
   In my opinion, having options is more flexible than adjusting to some default behavior that's why I have made write modes configurable. If you think this is overhead, we can always chose one default behavior for these readers since unfortunately currently they behave differently.

[rdblue]

I think we should make a decision and have a single default behavior instead of adding table properties. I don't see much value in being able to configure this differently across tables.

[arina-ielchiieva]

Closed in favor of PR #318.