feat: optimized udf build

[wey-gu]

The indent character was wrong, now it's fixed and tested.

What type of PR is this?

• bug
• feature
• enhancement

desc

• Fixed the indentation character from white space to tab character
• now, we could do make UDF=foo to build when we have foo.cpp and foo.h and it'll output foo.so

For docs update:

Example that could be used in docs

$ cd udf
$ ls standard_deviation*
standard_deviation.cpp  standard_deviation.h
$ make help
Usage: make UDF=<udf_name>
Example: make UDF=standard_deviation
$ make UDF=standard_deviation
g++ -c -I ../src/ -I ../build/third-party/install/include/ -fPIC standard_deviation.cpp -o standard_deviation.o
g++ -shared -o standard_deviation.so standard_deviation.o
$ ls *.so
standard_deviation.so

cc @cooper-lzy @abby-cyber @whitewum

Checklist:

Tests:

• Unit test(positive and negative cases)
• Function test
• Performance test
• N/A

Affects:

• Documentation affected (Please add the label if documentation needs to be modified.)
• Incompatibility (If it breaks the compatibility, please describe it and add the label.）
• If it's needed to cherry-pick (If cherry-pick to some branches is required, please label the destination version(s).)
• Performance impacted: Consumes more CPU/Memory

Release notes:

n/a

[abby-cyber]

ref: #4804