scripted-diff: Rename InitInterfaces to NodeContext

Summary:
-BEGIN VERIFY SCRIPT-
s() { git grep -l "$1" src | xargs sed -i "s/$1/$2/g"; }

s 'struct InitInterfaces' 'struct NodeContext'
s 'InitInterfaces interfaces' 'NodeContext node'
s 'InitInterfaces& interfaces' 'NodeContext\& node'
s 'InitInterfaces m_interfaces' 'NodeContext m_context'
s 'InitInterfaces\* g_rpc_interfaces' 'NodeContext* g_rpc_node'
s 'g_rpc_interfaces = &interfaces' 'g_rpc_node = \&node'
s 'g_rpc_interfaces' 'g_rpc_node'
s 'm_interfaces' 'm_context'
s 'interfaces\.chain' 'node.chain'
s '\(AppInitMain\|Shutdown\|Construct\)(interfaces)' '\1(node)'
s 'init interfaces' 'chain clients'
-END VERIFY SCRIPT-

This is a parial backport of Core PR16839 : https://github.com/bitcoin/bitcoin/pull/16839/commits/301bd41a2e6765b185bd55f4c541f9e27aeea29d

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D6108