[improve][build] Create source jar for pulsar-client-all shaded jar

[tisonkun]

This fixes #19918

Motivation

Create source jar for debugging and IDE integration.

Modifications

Set createSourceJar and shadeSourcesContent to true following https://maven.apache.org/plugins/maven-shade-plugin/shade-mojo.html.

Verifying this change

• Make sure that the change passes the CI checks.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository:

[codecov-commenter]

Codecov Report

Merging #19956 (3c16dfa) into master (cda2827) will increase coverage by 13.86%.
The diff coverage is 100.00%.

@@              Coverage Diff              @@
##             master   #19956       +/-   ##
=============================================
+ Coverage     58.92%   72.79%   +13.86%     
- Complexity    25921    31484     +5563     
=============================================
  Files          1846     1859       +13     
  Lines        136607   136836      +229     
  Branches      15033    15049       +16     
=============================================
+ Hits          80498    99611    +19113     
+ Misses        48645    29314    -19331     
- Partials       7464     7911      +447     

Flag	Coverage Δ
inttests	24.35% <100.00%> (?)
systests	25.20% <0.00%> (?)
unittests	72.08% <100.00%> (+13.16%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ulsar/broker/resources/LocalPoliciesResources.java	75.86% <100.00%> (ø)

... and 705 files with indirect coverage changes

[eolivelli]

+1