[v2] ClientSession runs on JSONRPCDispatcher; BaseSession removed #2698

Job	Run time
checks / readme-snippets	11s
checks / pre-commit	35s
checks / test (3.10, locked, windows-latest)	1m 45s
checks / test (3.11, locked, windows-latest)	1m 53s
checks / test (3.11, lowest-direct, windows-latest)	1m 28s
checks / test (3.11, locked, ubuntu-latest)	55s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 2s
checks / test (3.10, locked, ubuntu-latest)	51s
checks / test (3.14, lowest-direct, ubuntu-latest)	48s
checks / test (3.14, lowest-direct, windows-latest)	1m 41s
checks / test (3.14, locked, ubuntu-latest)	2m 0s
checks / test (3.10, lowest-direct, windows-latest)	1m 27s
checks / test (3.12, locked, windows-latest)	1m 22s
checks / test (3.12, lowest-direct, windows-latest)	1m 33s
checks / test (3.11, lowest-direct, ubuntu-latest)	51s
checks / test (3.14, locked, windows-latest)	2m 42s
checks / test (3.12, locked, ubuntu-latest)	45s
checks / test (3.13, lowest-direct, ubuntu-latest)	53s
checks / test (3.13, locked, windows-latest)	1m 30s
checks / test (3.10, lowest-direct, ubuntu-latest)	56s
checks / test (3.13, lowest-direct, windows-latest)	1m 10s
checks / test (3.13, locked, ubuntu-latest)	51s
all-green	5s
	27m 14s

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