terminfo: add status line capabilities: hs, dsl, fsl and tsl

* hs  - boolean, signals status line availability
* tsl - to_status_line: begin an OSC 2 sequence (set window title)
* fsl - from_status_line: OSC terminator
* dsl - disable status line: \E]2;\E\\ - clears the window title

Closes #242

CHANGELOG.md

@@ -92,6 +92,9 @@ means foot can be PGO:d in e.g. sandboxed build scripts. See
 * OSC 777;notify: desktop notifications. Use in combination with the
   new **notify** option in `foot.ini`
   (https://codeberg.org/dnkl/foot/issues/224).
+* Status line terminfo capabilities `hs`, `tsl`, `fsl` and `dsl`. This
+  enables e.g. vim to set the window title
+  (https://codeberg.org/dnkl/foot/issues/242).
 
 
 ### Changed

foot.info

@@ -16,6 +16,7 @@ foot+base|foot base fragment,
     bce,
     bw,
     ccc,
+    hs,
     km,
     mir,
     msgr,
@@ -59,11 +60,13 @@ foot+base|foot base fragment,
     dim=\E[2m,
     dl1=\E[M,
     dl=\E[%p1%dM,
+    dsl=\E]2;\E\\,
     ech=\E[%p1%dX,
     ed=\E[J,
     el1=\E[1K,
     el=\E[K,
     flash=\E]555\E\\,
+    fsl=\E\\,
     home=\E[H,
     hpa=\E[%i%p1%dG,
     ht=^I,
@@ -265,6 +268,7 @@ foot+base|foot base fragment,
     smul=\E[4m,
     smxx=\E[9m,
     tbc=\E[3g,
+    tsl=\E]2;,
     u6=\E[%i%d;%dR,
     u7=\E[6n,
     u8=\E[?%[;0123456789]c,