Improve IKEv2/IPsec VPN by proposing more IPsec algorithms

This commit allows IKEv2/IPsec VPN to propose more algorithms that
newly added in IpSecAlgorithm. Those new algorithms have stronger
security guarantees and better performances.

This commit also removes algorithm name validation because all
algorithms are URL encoded to ensure no special characters create
problems due to their use by VpnProfile for list or field delimiting
(e.g. rfc7539esp(chacha20,poly1305))

Bug: 185265778
Test: atest FrameworksNetTests, CtsNetTestCases
Test: All new algorithms are manually verified
Change-Id: I1de322c95aacc8924e95bcdbcfdbd1ec441de99c