arrow

ARROW-11026 [Rust]: Run tests without requiring environment variables

This PR is based on @mqy 's great work in: https://github.com/apache/arrow/pull/8967.

(If we want to take this PR, we can either merge it in to https://github.com/apache/arrow/pull/8967/files# directly or I can make a new independent PR when that is merged).

## Rationale
The outcome is that developers can now simply run  `cargo test` in a typical checkout without having to mess with environment variables. I think this will lower the barrier to entry for people to contribute.

## Changes
1. Code from https://github.com/apache/arrow/pull/8967 to encode heuristics of where to check for test data
1. Remove all references to ARROW_TEST_DATA and PARQUET_TEST_DATA and uses the test_util methods instead
2. Update the comments / error messages in test_util

## Example Error Handling

Error handling: here is what happens with a fresh checkout and no git modules checked out  and no environment variables set:

```
cargo test -p arrow
---- ipc::reader::tests::read_decimal_be_file_should_panic stdout ----
thread 'ipc::reader::tests::read_decimal_be_file_should_panic' panicked at 'failed to get arrow data dir: env `ARROW_TEST_DATA` is undefined or has empty value, and the pre-defined data dir `/private/tmp/arrow/rust/arrow/../../testing/data` not found
HINT: try running `git submodule update --init`', arrow/src/util/test_util.rs:81:21
```

Here is an example of what happens when `ARROW_TEST_DATA` is pointing somewhere non existent

```
ARROW_TEST_DATA=blargh cargo test -p arrow
...
--- ipc::reader::tests::read_decimal_be_file_should_panic stdout ----
thread 'ipc::reader::tests::read_decimal_be_file_should_panic' panicked at 'failed to get arrow data dir: the data dir `blargh` defined by env ARROW_TEST_DATA not found', arrow/src/util/test_util.rs:81:21
```

Closes #8996 from alamb/alamb/tests_without_env

Authored-by: Andrew Lamb <andrew@nerdnetworks.org>
Signed-off-by: Neville Dipale <nevilledips@gmail.com>