ARROW-10188: [Rust] [DataFusion] Fixed DataFusion examples.

[jorgecarleitao]

Also renamed an example, that refered to the old name "table_api".

[github-actions]

https://issues.apache.org/jira/browse/ARROW-10188

[alamb]

I ran the examples where code was modified, and they look good to me!

The comment updates also seem like a good improvement.

alamb@ip-192-168-1-129:~/Software/arrow/rust/datafusion$ PARQUET_TEST_DATA=`pwd`/../../cpp/submodules/parquet-testing/data ARROW_TEST_DATA=`pwd`/../../testing/data cargo run --example csv_sql
    Finished dev [unoptimized + debuginfo] target(s) in 0.17s
     Running `/Users/alamb/Software/arrow/rust/target/debug/examples/csv_sql`
+----+----------------------+--------------------+
| c1 | MIN(c12)             | MAX(c12)           |
+----+----------------------+--------------------+
| a  | 0.02182578039211991  | 0.9567595541247681 |
| e  | 0.01479305307777301  | 0.9965400387585364 |
| d  | 0.061029375346466685 | 0.9748360509016578 |
| c  | 0.2667177795079635   | 0.991517828651004  |
| b  | 0.04893135681998029  | 0.9185813970744787 |
+----+----------------------+--------------------+

alamb@ip-192-168-1-129:~/Software/arrow/rust/datafusion$ PARQUET_TEST_DATA=pwd/../../cpp/submodules/parquet-testing/data ARROW_TEST_DATA=pwd/../../testing/data cargo run --example dataframe
Compiling datafusion v2.0.0-SNAPSHOT (/Users/alamb/Software/arrow/rust/datafusion)
Finished dev [unoptimized + debuginfo] target(s) in 4.18s
Running /Users/alamb/Software/arrow/rust/target/debug/examples/dataframe
+----+----------+---------------------+
| id | bool_col | timestamp_col |
+----+----------+---------------------+
| 4 | true | 1235865600000000000 |
| 5 | false | 1235865660000000000 |
| 6 | true | 1238544000000000000 |
| 7 | false | 1238544060000000000 |
| 2 | true | 1233446400000000000 |
| 3 | false | 1233446460000000000 |
+----+----------+---------------------+

alamb@ip-192-168-1-129:~/Software/arrow/rust/datafusion$ PARQUET_TEST_DATA=pwd/../../cpp/submodules/parquet-testing/data ARROW_TEST_DATA=pwd/../../testing/data cargo run --example simple_udaf
Finished dev [unoptimized + debuginfo] target(s) in 0.16s
Running /Users/alamb/Software/arrow/rust/target/debug/examples/simple_udaf
The geometric mean of [2,4,8,64] is 8

I also ran the other examples locally and they compiled and produced output