[C++] Adding ToProto for ExtensionSet

[asfimport]

ExtensionSet needs to be converted ACERO->Substrait. 

{}substrait::extension::SimpleExtensionURI{`}`, {}substrait::extensions::SimpleExtensionDeclaration{} and ``{}substrait::extensions::AdvancedExtension{} needs to be created by using an existing `ExtensionSet` object. 

Reporter: Vibhatha Lakmal Abeykoon / @vibhatha

_{Note: This issue was originally created as ARROW-16896. Please see the migration documentation for further details.}

[asfimport]

Vibhatha Lakmal Abeykoon / @vibhatha:
I think once this feature is implemented, we can replace what is in the Status AddExtensionSetToPlan(const ExtensionSet& ext_set, substrait::Plan\* plan)[1] function by the set of functions written in this PR. 

[1]

arrow/cpp/src/arrow/engine/substrait/plan_internal.cc

Line 38 in 8691580

Status AddExtensionSetToPlan(const ExtensionSet& ext_set, substrait::Plan* plan) {

 

cc @westonpace  

[asfimport]

Vibhatha Lakmal Abeykoon / @vibhatha:
@westonpace  I think this is no longer needed. WDYT? 

[asfimport]

Apache Arrow JIRA Bot:
This issue was last updated over 90 days ago, which may be an indication it is no longer being actively worked. To better reflect the current state, the issue is being unassigned per project policy. Please feel free to re-take assignment of the issue if it is being actively worked, or if you plan to start that work soon.

[github-actions]

This issue has been marked as stale because it has had no activity in the past 365 days. Please remove the stale label or comment below, or this issue will be closed in 14 days. If this improvement is still desired but has no current owner, please add the 'Status: needs champion' label.