[AURON #1613] Introduce AuronExtFunctions

[Tartarus0zm]

Which issue does this PR close?

Closes #1613 .

Rationale for this change

Currently, all extension functions in Auron are designed for Spark, Therefore, it is named SparkExtFunctions.
We are advancing multi-engine support for Auron, so the name SparkExtFunctions no longer meets our requirements.
Therefore, I suggest rename it to AuronExtFunctions.
Function Names for Native Implementations, I recommend using the following rules:

• If it's only used by Auron and not integrated with other engines, then use standard naming conventions, such as Placeholder;
• if used for spark should be start with 'Spark_', such as Spark_Murmur3Hash;
• if used for flink should be start with 'Flink_', such as Flink_UNIX_TIMESTAMP;
• same to other engines.

What changes are included in this PR?

• rename SparkExtFunctions to AuronExtFunctions
• add prefix of Spark_ for spark native functions

Are there any user-facing changes?

No.

How was this patch tested?

Test via CI

[Tartarus0zm]

@richox @SteNicholas @zuston @merrily01 CI is green, PTAL

[SteNicholas]

LGTM.

[merrily01]

Merged. Thanks @Tartarus0zm