improve diff view of long string values

it would be pretty awesome to improve how we show diff for long string values, especially when they are wrapped in the terminal. for example

```diff
--- update configmap/linkerd-config (v1) namespace: linkerd
...
2, 2 global: |
3 - {"linkerdNamespace":"linkerd","cniEnabled":false,"version":"stable-2.3.2","identityContext":{"trustDomain":"cluster.local","trustAnchorsPem":"-----BEGIN CERTIFICATE-----\nMIIBgjCCASmgAwIBAgIBATAKBggqhkjOPQQDAjApMScwJQYDVQQDEx5pZGVudGl0\neS5saW5rZXJkLmNsdXN0ZXIubG9jYWwwHhcNMTkwNjE4MTk1NDQzWhcNMjAwNjE3\nMTk1NTAzWjApMScwJQYDVQQDEx5pZGVudGl0eS5saW5rZXJkLmNsdXN0ZXIubG9j\nYWwwWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAASlDwpe0E2UvdTc+nuXnmUbHTRM\nk8ozZwGDvgYR/WVcnwnFUCHpNdt4lqaker3YZBdqXBYqN8/PW413xjfvHB8yo0Iw\nQDAOBgNVHQ8BAf8EBAMCAQYwHQYDVR0lBBYwFAYIKwYBBQUHAwEGCCsGAQUFBwMC\nMA8GA1UdEwEB/wQFMAMBAf8wCgYIKoZIzj0EAwIDRwAwRAIgRY0aVzBiDmscwK6G\n2zVcsFSJD6bhVf/Dqfws/ljCeBECIC8bWlkBRMhebYl4tSPH/IwiNXDXVCRgO/jz\n6iLVXPjv\n-----END CERTIFICATE-----\n","issuanceLifetime":"86400s","clockSkewAllowance":"20s"},"autoInjectContext":null}
3 + {"linkerdNamespace":"linkerd","cniEnabled":false,"version":"stable-2.3.2","identityContext":{"trustDomain":"cluster.local","trustAnchorsPem":"-----BEGIN CERTIFICATE-----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\n6iLVXPjv\n-----END CERTIFICATE-----\n","issuanceLifetime":"86400s","clockSkewAllowance":"20s"},"autoInjectContext":{}}
4, 4 install: |
5 - {"uuid":"a3d53c7f-04cd-4110-85c1-2852e3d795c1","cliVersion":"stable-2.3.2","flags":[]}
5 + {"uuid":"a3d53c7f-04cd-4110-85c1-2852e3d795c1","cliVersion":"stable-2.3.2","flags":[{"name":"proxy-auto-inject","value":"true"}]}
```