feature:support auto proxy of DataSource

[xingfudeshi]

Ⅰ. Describe what this PR did

1.Simplify the Spring Integration,the only thing you need to do is define a bean of GlobalTransactionScanner.
2.Add a switch ：spring.datasource.autoproxy,the default value is false
3.Unify file.conf.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)?

I've done the integration testing.

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-io]

Codecov Report

Merging #1496 into develop will decrease coverage by 0.07%.
The diff coverage is 9.52%.

@@              Coverage Diff              @@
##             develop    #1496      +/-   ##
=============================================
- Coverage      46.45%   46.38%   -0.08%     
  Complexity      1692     1692              
=============================================
  Files            347      348       +1     
  Lines          12711    12729      +18     
  Branches        1586     1588       +2     
=============================================
- Hits            5905     5904       -1     
- Misses          6167     6185      +18     
- Partials         639      640       +1

Impacted Files	Coverage Δ	Complexity Δ
...ava/io/seata/core/constants/ConfigurationKeys.java	0% <ø> (ø)	0 <0> (ø)	⬇️
...g/annotation/datasource/DataSourceProxyHolder.java	0% <0%> (ø)	0 <0> (?)
...ta/spring/annotation/GlobalTransactionScanner.java	51.4% <15.38%> (-5.3%)	17 <1> (ø)
...server/store/file/FileTransactionStoreManager.java	45.99% <0%> (-0.35%)	19% <0%> (ø)

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[slievrly]

The overall functional test passed, but when using the druid configuration init-method will report an error.
init-method="init" destroy-method="close"

[xingfudeshi]

The overall functional test passed, but when using the druid configuration init-method will report an error.
init-method="init" destroy-method="close"

done.

[slievrly]

test function pass. Pls add this configuration item in nacos-config.txt

[xingfudeshi]

test function pass. Pls add this configuration item in nacos-config.txt

it's done.

[slievrly]

LGTM

[zjinlei]

LGTM