[SPARK-13582] [SQL] defer dictionary decoding in parquet reader

## What changes were proposed in this pull request?

This PR defer the resolution from a id of dictionary to value until the column is actually accessed (inside getInt/getLong), this is very useful for those columns and rows that are filtered out. It's also useful for binary type, we will not need to copy all the byte arrays.

This PR also change the underlying type for small decimal that could be fit within a Int, in order to use getInt() to lookup the value from IntDictionary.

## How was this patch tested?

Manually test TPCDS Q7 with scale factor 10, saw about 30% improvements (after PR #11274).

Author: Davies Liu <davies@databricks.com>

Closes #11437 from davies/decode_dict.